Hey guys, been awhile since I've been on here cuz I haven't had any problems!

Recently my truck started stalking at idle only if I rev it and then let it bring it back down to 600rpms. If I gradually let it down it will not stall, but if I punch it then let off it will completely stall. It also is the same if I am in drive and start going then let off. It will not stall on acceleration unless I hit around 4K Rpms then it completely stops firing like everything goes dead. After about 3 seconds after I let off it will return to my speed rpm ratio that you usually would be at because the wheels are forcing things to turn. Counting my shifts I'm almost positive my torque converter is not locking up.

It idles perfectly. Actually great! So it's safe to say there is no grounding of the spark or distributor bad or injectors clogged... Fuel pressure stays constant always. I checked with a fuel pressure gauge. So relay isn't bad either or pump.

I guess a sensor could be bad? I just put a new IAC in. I also just did the plenum fix. However, this problem was going on BEFORE that. I did the plenum fix thinking it might be the issue. All fuses are good. Bad O2 sensor? I don't even have the back one hooked up...

Oil pressure is well and also the voltmeter always stays at 14. PCM has got some issues of its own...I have a new one but don't wanna put it in until this is resolved. I don't wanna take a chance and blow it. It has an internal fault error it reads. But I think once again since it idles and everything fine why would it run great and stall just on a rev. I'm thinking some sensor it's gotta be... Maybe I can check an injector and see what's going on when it stalls? Well...I guess they stop objecting lol. Something has got to be telling them to stop hence a sensor. In park or neutral it even revs very nicely it's just once you let off it dies. I think that's about all I got for description!

 

Per my Haynes manual I just checked for TPS signal voltage and all 5.2V are accounted for.

 

What brand IAC? I got one from the parts store, and my truck would occasionally stall at stops. Replaced it with a mopar piece, problem is gone.

 

^+1
Aftermarket sensors can be very hit and miss for quality and longevity.
I get Mopar sensors and avoid the whole question.
The added initial expense is saved when you don't have to keep changing them out, or start changing other components thinking the sensor is fine cuz you just changed it.

 

It was Autozone. I still got the old one that I'm assuming is oem but no promises. It was disgusting and I had the new one so I thought I'd swap.

 

It idles great though! That's where I'm stuck! I took the maf off and used maf cleaner wondering if that was the problem. If I unplug the TPS it runs terrible but it will lessen the amount of times it stalls when I let off. If I still punch it and let off it still stalls with it u plugged tho. Idk where that one is from.

I didn't have any issues other than bad mpg (9) and burning oil and I took it trailing and went thru some water and I had a couple sputters, but then it was fine. I just redid the plenum so there's not any junk in it or the valley. I didn't submerse or anything, just had some water come onto the plugs and make them miss. They are all dried out now and it idles great. I pulled some and checked them: they're your normal burnt maybe Alittle bit of oil from the burning oil problem and I think some coolant but that's all done. Gotta be a sensor right? I'd think since it idles and revs fine that they are ok... It's the engine deceleration that kills the engine. Like the sensors don't k ow what's going on. Thanks guys

 

I was looking up how an IAC works and now I'm wondering, if I pull it off the I take but then plug it back in, I should be able to see the plunger moving in and out, correct? It's a mechanical part with no sensors so it doesn't know any difference... Maybe it would have to be grounded out but that's all I can think of. Any thoughts, suggestion?

 

Don't do that. As soon as you turn the key, the PCM will attempt to close it off, and launch the pintle. After that, it is scrap.

The trouble with the aftermarket sensors, at least, the biggest problem I saw, is they simply don't react fast enough. If they have time to adjust themselves to conditions, sure, it *works*.... but, if it needs to open fast, to prevent a stall, it can't.

On mine, that was the ONLY thing I changed..... and it solved the problem.

MAF cleaner does nothing for a map sensor. MAF is Mass Air FLOW. The filament needs to be clean to get an accurate reading. MAP is manifold absolute pressure. It doesn't care if it is dirty or not.

 

Sorry I did mean MAF. And ok I see what you mean. I believe that is right because of the next diag I did: I removed all vacuum lines from their nipples on the manifold, except the brake booster and pcv valve, and it idles Alittle high at 800, however never would stall. So this is sounding like I need a genuine oem mopar iac after hearing this? And what you said of course..

 

I do have my cruize and Evap permanently unnattatched... If anything tho they would create more resistance or vaccuum should I say. As I unplug accessories from the manifold it gets better