About a week ago my truck started running like hell. It was idling rough, bogging out occasionally, rpms bouncing wildly, hesitation on acceleration, erratic transmission shifting, and an occasional lack of overdrive. In addition, my cruise control stopped working, and the airbag light came on. The PCM was throwing no codes.
I started surfing threads to gather as much information as I could to figure out where to start on my repairs.
I ordered parts, dedicated a weekend, and went to getting my hands dirty. Here's everything I did:

Gutted Cat
Rear O2 Sensor non fouler trick.
Cleaned throttle body and intake manifold thoroughly
Replaced:
- TPS
- IAC
- Upstream O2 sensor
- Spark plugs (Bosch Platinum Fusion)
- Spark plug wires (Bosch Platinum)
- Coil (Accel high performance)
- Distributor cap and rotor (Accel)
- Hughes plenum kit (plenum WAS blown)


After I put everything back together I chased fuel leaks and vacuum leaks on my fuel rails and injectors. Fixed the fuel rail and replaced all injector o-rings.

For the most part, my problems disappeared. However, occasionally still, the truck will start bogging, the rmps will jump around, and the truck will start shuddering. Also, after the truck warms up the rpms will constantly and steadily fluctuate by about 200 at idle. The truck is throwing code P0121, which I know has to do with the TPS. Could a bad MAP sensor (the one sensor I didn't replace) be causing the code?

I still have no cruise control and an airbag light, and am fairly certain that the culprit is a broken clockspring. Could this be causing the occasional bogging? (electrical short?)

 

If you are getting a TPS code, test the TPS.......

 

And if you have no cruise control, check the vac line going to the CC servo under the battery tray.

 

I tested the TPS with a volt meter and everything read the way it should. That's why I asked about the MAP sensor. I read something about the MAP and TPS reading off each other, and one malfunctioning can throw the other off?
I've also checked all the vacuum lines and check valves I could find, including the CC servo under the battery tray. I'm 99% certain the cruise control is an electrical issue, because the little green light on the button won't even turn on. Ocassionaly when I turn the steering wheel the cruise control light will come on, and / or the airbag light will turn off momentarily. That's why I was thinking the clockspring is to blame.

This whole thing just really has me scratching my head and throwing the occasional 4 letter profanity. Haha. Sucker was doing the same bouncy idle all the way to work this morning.

 

Sounds like a bad CS to me..... If you don't mind farking about with air bags, you can test it..... procedure is in the service manual.

 

I went ahead and replaced the MAP sensor. Made no difference in the engine's performance, however it did seem to clear the trouble code for the TPS. Need to drive around some more to be sure that the code doesn't reappear.

I ordered a clock spring, so I'll see if that makes any difference when it arrives and I install it.

A new issue I'm having though is the torque converter is acting funny. At speeds between 30 and 40 mph, the TC locks and unlocks almost constantly. Then after driving at hwy speeds, the TC doesn't want to unlock until I come to a complete stop. If I take my foot off the accelerator while driving down the highway I can hear the engine braking, as if I let off the gas without depressing the clutch on a manual transmission. Also occasionally while the truck is slowing down from higher speeds, it will actually downshift into each gear range by itself. What could be causing this??

 

Check this out, might help. https://dodgeforum.com/forum/2nd-gen...agnostics.html

 

Thanks zman. I've actually seen that thread, just forgot it existed. Pretty sure all my issues are electrical now. Going to replace the clock spring and if that doesn't work I'll put in a new brake light switch, and then a new computer.
I'll keep yall posted on how things turn out.
Thanks for the help so far.

 

ok im a little stumped. i have a similar issue only mine is a racing idle. meaning my idle was at 2250rpm. i replaced the IAC and immediately got the idle down to 1250rpm. i know it should idle around 750/800rpm.

i changed:
IAC
TPS with new gasket
took out and cleaned throttle body.
tried clearing computer memory.

still idling at 1250. any ideas what could be the cause? i dont have a scanner as of yet.

any info is helpful-thanks in advance

 

A failed coolant temperature sensor will do that. The PCM thinks the world is really, really cold when that happens.