So after going through lots of threads on here and on google, i decided to make an account because i cant figure out the issue. My 1995 5.9 randomly a few moths ago stalled at a stop light, and ever since then it stalled every time i went to shift from Park to Drive or Reverse, and does not stay running upon starting it unless i have my foot on the gas to raise the rpms. I can keep it running in idle if i start it while simultaneously pressing on the gas to raise the rpms and then releasing my foot. However also in idle, the instant i even SLIGHTLY touch the gas after that fact, it dies. I will note that it shifts and runs fine, as it always has, and i have been driving it like this for awhile now because i couldnt diagnose it. To help you out and save you from suggesting something i already tried, i will list below what i have already done to try to fix the issue.

1. Replaced the IAC, twice actually
2. replaced TPS
3. Battery is fine, voltage is normal
4. Alternator is fine, its new
5. fuel pump fine, Fuel pressure is normal, i checked it
6. No check engine light

I bought a crankshaft position sensor to replace my current one, but 1)i cant find it even using some diagrams i found and 2) idk if thats the issue anyway? Also thought it was a vacuum leak, but that wouldnt cause it to give these issues because the IAC and computers would no doubt try to compensate and adjust for the leak i think. Any help would be appreciated! Thanks, Steve

 

First thing is, these engines don't like aftermarket sensors. At all. Your IAC might be 'new', but, if it ain't a mopar part, it likely isn't working the way the computer expects.

The whole 'dies when shifting from park to any gear' thing, *usually* indicates a failing crank sensor, but, if it runs good otherwise, and doesn't just die on you randomly while driving, restarts right away, that likely is ok. Its located behind the passenger side head, and extends down into the bellhousing. It reads from the flexplate.

Next question would be: Did you THOROUGHLY clean the throttle body when you changed the IAC?? A lot of crap tends to build up in there, and the computer can only compensate so much. So, try this. Disconnect the battery, pull the throttle body, and clean the snot out of it. (new gasket too please, they are only a couple bucks.) When you have it all back together, battery connected, etc, turn the key to "on", count to ten. Don't touch anything. This lets the PCM re-learn the 'zero' values for various sensors. NOW start the truck. It *should* relearn idle pretty quickly. If it doesn't, we can dig deeper.

Welcome to DF!

 

Thank you for the reply! Yes i thought the same, so i replaced the IAC the 2nd time with an oem one. Still nothing changed unfortunately

As for the crank sensor reply: So no, it wont die if my foot is on the gas. However the instant i let off (even while coasting) the rpms will drop, oil light comes on, and it will die if i dont quick give it gas to bring it back to life. Same when rolling to a stop to be in idle..it will die and i'll have to restart it. It wont restart unless i give it gas and keep my foot on it to keep the rpms up. I'll keep trying to find it (the sensor) but no luck yet. Apparently its pretty hard to access from what i read

I did clean the throttle body when i took it all off, yes. I used carb cleaner, cleaned it nicely, and also did seafoam treatment too. Upon the new IAC's being installed, it did its normal thing for 30secs or so (hissing and adjusting at a high rpm, similar to how a cold start sounds), but then it just went back to normal, which is dying when touching the gas

 

Also, yes i did attempt the whol pcm resetting thing as well. And i forgot to mention some other symptoms when it is idling in a cold start. So, it runs pretty rough, you can hear it doesn't sound normal. The rpms will also go up and down...fluctuating enough to hear it from a distance. I'll add those two symptoms along with what i mentioned in my OP

 

Also i did reply to your whole message btw, for some reason it needed approved first i think. But yes i did reply to your whole message, not just the end part

 

You have a vacuum leak somewhere..... Check the plenum? There is a thread about that stickied at the top of this forum.

 

I checked briefly and it doesnt seem the line up with what i have. They claim coolant leaks, engine overheating..etc. I do burn a bit of oil, but i thought that was common in the 5.9's. I guess i can stick my snake camera into the throttle body. What should i look for? On that same note, one way to find a vacumm leak on lines is to spray carb cleaner or sea foam and see if the idle changes or stalls, thus showing you where the leak is. Is there any way to do that with the plenum gasket? Or is that buried internally?

 

Plenum gasket is on the bottom of the intake manifold. No access to it without pulling the intake. (and then you might just as well fix it. ) If you see oil pooling in the back of the intake, gasket is blown. And I agree, just a vacuum leak shouldn't cause the engine to die if you step slightly on the gas...... Test the TPS??

 

Yep i replaced the TPS after the IAC was replaced. I guess it didnt need replaced since nothing changed? Along with what i already said above, does the following help? So before all this, sometimes when i would put it in reverse and hit the has to back up...and then let off the gas to coast, it would stall. This was only occasionally, and not too often. But, it was before all the things mentioned above started happening full time. Just trying to give as much info as i can. I'd rather not do the plenum gasket if its not the case lol doesnt look too fun

 

Oh, come on, it's a BALL!

Sometimes, a failing crank sensor will allow the engine to run, till you ask it to do something...... (like, if you put it in reverse....) Your symptoms don't match up precisely though.... so I would be hesitant to recommend replacement at this point..... Got a scanner that can read live data??