So here is my problem, and I have had this issue with this truck for as long as I have owned it, over 4 years now. It is a 1998 5.2L 4x4 Dakota Sport with a manual transmission and 139k miles.

The truck has this weird problem where once it is warmed up and you are driving if you take it out of gear (it is a manual) the tach will drop like it should, go below the idle point and the computer will compensate and make it bounce up then it tries to settle down again and does this a few time before it settles a little below 600 RPM, at that level it makes the oil pressure drop on the guage and the truck begins to discharge from around 14V at charging to the 6-8 volt range, the headlights, interior lights and heater all slow down as well. I have changed sensors left and right to no avail. Here is a list of what I have done to it for this problem:

Replaced plugs, wires, cap and rotor.
Replaced TPS and two IACs.
New plenum pan (Hughes Aluminum) and all new gaskets
New upstream O2 Sensor
New battery
Removed and cleaned throttle body
Checked all vacuum lines, getting around 15 at idle
Rerouted plug wires per TSB

The truck has plenty of power and doesn't seem to hiccup. I have tested the TPS with an ohmmeter, no flat spots. I can see the IACV operating. When I replace it, it acts better for awhile then the behavior returns. The only code I receive is for my cruise control solenoid circuits P1595, only intermittently. Intermittently the cruise won't work, although more often than not it does and shouldn't affect the idle as it is off most of the time. Probably just need to replace the cruise unti. Another thing I notice is if I am parked and rev the motor up to 3-4k and let it come back down the truck will sputter and stall. When I come back from skiing and come to a stop back in town or just put the clutch in to coast or downshift, in cold weather with the truck warmed up and driving for 30+ minutes, take it out of gear to stop it will bounce and stall.

Also I notice when it I first start it up in the morning and pull out of the driveway when it is cold, as I put it in 1st and take off it kind of sputters like it isn't getting fuel for a second, but I never have this problem at any other time, the throttle response is good. I am thinking maybe a little oil pools in the intake overnight or some moisture?? I dunno?? The only thing I have left to think of is the PCM is bad??? If so, I want to do a replacement with the folks in Florida at Auto Computer Exchange, but should I get a refurbed one or send them mine to be repaired? I am tired of throwing money at this truck for this and it is driving me crazy. Otherwise it has been a great truck, it is paid for and I want to drive it. Anyone have any experience with this or other ideas???

My truck does the same exact thing. Coming up to a stop with the clutch pushed in the RPM's will bounce until I come to a complete stop. And some times, at night, if I have enough accessories on the RPM will bounce low enough to almost cause the engine to stall.

I've noticed though that if I'm coming up to a stop and push in the clutch below 800 RPM then I do not get the bounce. And if I have my A/C running and again coming up to a stop the RPM's will not bounce. Nor will they bounce if the truck isn't completely warmed up yet.

But outside of that the truck runs perfectly fine.

I've replaced everything you have and can add the following:

New 52mm TB
New MAP sensor
New rear o2 sensor
New coil
New headers and exhaust system
Replaced clutch fan with electric fan

What I have not replaced is the transmission output sensor and ABS sensor in the rear diff and the crank and camshaft sensors. My suspicion has always been that it's the trans output or rear diff ABS sensors (that detect speed) that's the cause. I just never seem to find time to replace them.

Hmm, hadn't thought about either of those.... that just reads the output speed of the transmission rotation right?? My transmission is a little rough as I engage the next gear so that could be a possibility, although I think it is just my clutch... getting to where it releases near the top of the pedal motion now. Isn't that sensor only for an automatic transmission though? I haven't done the crank or camshaft sensors yet either. Don't want to replace sensors if it is unnecessary, but I really want to get the problem solved!

It looks like the WSS (Rear Wheel Speed Sensor) in the rear axle provides output to the CAB (Controller Antilock Brakes) and then from the CAB to the PCM for the cruise control and probably more.


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Vehicle speed and distance covered are measured by the Rear Wheel Speed Sensor. The sensor is mounted to the rear axle. A signal is sent from this
sensor to the Controller Antilock Brake (CAB) computer. A signal is then sent from the CAB to the Powertrain Control Module (PCM) to determine vehicle speed and distance covered. The PCM will then determine strategies for speed control system operation.
*********************************

I had thought there was a transmission mounted speed sensor but I can't find anything for the NV3500. It looks like maybe only the auto's have the speed sensors in the trans.

Thanks for the reply. Yes upon looking further the NV3500 doesn't have the transmission output speed sensor so the RWSS is probably the next direction ($40). Especially since I am getting the P1595 code and the cruise is a bit finnicky. The Dodge dealer parts guy recommended the camshaft and crank position sensor too, so probably go that route, those suckers are a bit more pricey! Of course he wants me to go into the stealership for service haha!

UPDATE: Not the RWSS, pulled mine and tested it, registered 1.8k Ohms, right in range where it should be. Normally if failed they read as open and set off the ABS and Brake lights. Guess it is camshaft or crank sensors next

Good luck with it and let us know what you find. There are a few others on some other sites that have had similar issues but no one ever seems to figure it out. Once the weather gets nicer I will continue with trying to figure it out. I may also clean up every single one of my grounds to see if that helps.

Something interesting today, got a P0545 code - Exhaust Gas Temp too low, never had this code in the past. There is some confusion online about it being for the A/C clutch as well, however my A/C clutch works perfectly. I had already ordered a post cat O2 sensor, since I just replaced the pre cat O2 sensor when I did my plenum, should get it next week. Might be on to something, anyone had this code and found a resolution to it on these trucks???

Well, I wanted to report back on a new situation.

On Tuesday morning I put new tires on the truck. They are the original size that came on it (235/70R15). They are the Firestone Indy 500's and so far they ride and handle pretty good. Anyway, the tires that I had on it before were 235/75R15 General Grabber AT2's. Definitely a taller tire. I was going to lift the truck but have since decided to go lower this summer.

I didn't notice until this morning but my RPM's didn't bounce once during a 30 mile roundtrip drive to go get coffee. As a matter of fact when coming to a stop with the clutch pushed in the RPM's actually stayed up and came down the slower I went until I came to a complete stop.

I'm not going to call this fixed yet. I'll give it another week or two of driving but my RPM bounce may have been caused by the taller tires.

Huh, that is interesting. Would be a weird fix but if it works then that is great! I have 31X10.5X15s on mine, no lift kit or any mods like that. I did solve the P0545 code - The A/C Relay was bad, swapped with the horn relay and the code went away. Guess some OBDII code readers have the wrong statement of what that code means. I am waiting for my post-cat O2 sensor to get here to swap that out and see if it makes any difference. I also noticed on my OBDII scanner that my catalyst monitor is not reporting OK, thinking the post-cat O2 sensor has something to do with that, might not be switching quickly enough. Seems like I get the same readings for voltage on the post cat O2 no matter what, although my scanner isn't very quick at showing the changes.

BTW, that is a long trip for coffee! Although I enjoy just getting out for a drive on a day off for coffee too Did you have a weather change where you are, mine acts up more when it is cold outside/winter time. Like you when I have the A/C on in the summer it is just fine.

Going to the pull a part yard this weekend, see if I can track down some other sensors to play with for testing and a few other cosmetic items. Keep you posted on any new developments.

I live in BFE so going anywhere to get anything is at least 20 miles. But it's at 65 - 75 mph speeds so it's not to bad.

Nope, no weather change. Still cold with snow on the ground unfortunately. I'm ready for some warmer weather.