So, interestingly this went away for like a year with no further work. Unfortunately it has since returned, so I though I would resurrect this thread in hopes of getting it figured out.

I've got access to live data through HP Tuners VCM Scanner, let me know what live data you would like to see.

What is happening is that for whatever reason, sometimes when the truck comes to a stop the fuel mixture will get richer and richer and richer(judging by the sensor output). You can watch the live data for the idle air control valve as it rapidly starts opening more and more to offset the extra fuel, but then it gets to where it's maximally open and more fuel is still coming in so the truck stumbles and eventually chokes out and dies if you don't open the throttle and let in more air.

So something is going on that is making the engine see too much fuel. The weird thing is that it doesn't happen every time you stop. It's becoming more regular, but it's not 100% of the time.

I suspect I have a vacuum leak somewhere because I also experience the wild vents(cruise works though). I made a homemade smoke machine to test for vacuum leaks and I am not seeing any...

Checked o2 fuse in PDC, it's good.

 

Vacuum leak could be under the dash, and some smoke machines don't make good enough smoke. What does the front O2 sensor do?

 

I was making some pretty good smoke and watched the dash like a hawk to see if I saw any coming out...nothing.

Not sure what you mean by "what the does the front o2 sensor do?" It tells the PCM how to regulate air/fuel ratio by leaning out or enrichening the mixture.

In other news, I unplugged the upstream o2 sensor (forcing open loop) and it idles fine. Can it really be the damned sensor again? This is like the 3rd NTK sensor in 7 years.

 

I know what it does, I was asking what it does when it starts to flood itself. If you unplug it and the symptoms go away then you found your problem.

 

I'm just having a hard time blaming the sensor again since this seems to be a pattern failure. Seems like there is something causing the sensors to go nutty.

 

How many miles per year do you drive your truck?

Unplugging the O2 sensor forces open loop, therefore, the problem stops. Doesn't necessarily mean the sensor itself is the underlying problem though. (though it is the most likely culprit) Have a look at ECT, and IAT sensors while the problem is presenting itself. See what they are doing. TPS *might* also be responsible, but, I find that rather unlikely..... (but still worth checking....)

 

What year is yours? What are your long n short term trims when this condition happens and engine coolant temp and intake air temp? Here's a couple'o things that I found in my years of the dodge magical mystery tour. I had the dreaded idle stalling problem in the past as well. Intermittent and frustrating to narrow down. One day, I noticed my intake air temp sensor was yet again coated with oil. I'd already done the plenum fix, but the PCV was aftermarket, not mopar. My PCV port at the intake, sucked in so much oil that once again the oil pooled on the floor of the intake. I've long since added an oil catch can n a mopar PCV n now...dry times in my plenum. Anyhow, I cleaned the IAT sensor and voila, no more sucking sounds akin to the IAC failings. Also, if you have access to a bi-directional scanner, check your fuel sync. My 96/5.2 would "mysteriously" stall roughly once every week/other week. No one seemed to know what caused it, but about 9 months ago, I reset my fuel sync n I haven't had even so much as 1 mystery stall in some 9 months now.

 

Let's see, I bought it 7 years ago with 135k and now it's at 179k, so about 6500 miles/year.

Coolant temp appears to be reading correctly (both on the gauge and laptop). I'll check out the IATs. TPS is correct, I watched the live data for that, when I close the throttle it goes to 0 and when I open it it seems to track correctly.

2001

For whatever reason my laptop won't show me the fuel trims. I have the option to add them, but the data is blank.

PCV is mopar, not that old, still functioning well. I'll look at the IAT to see if it's dry, but I suspect it is since the plenum is dry. I had a catch can on it, but it was a cheap one and it leaked vacuum so I took it off.

I don't have the ability to see fuel sync, but I do notice the timing advance jumps around a fair bit at idle between like 0 and 15 degrees. It's constantly moving. When you're on the throttle it's stable. It moves depending on MAP and Throttle input but it doesn't jump around all the time. Not sure if that's normal. I think that is typically a symptom of a worn timing chain, but again, mine is a melling double roller with maybe 25k on it, so I don't think that's an issue.

 

Without the fuel trims, you're almost flying blind. Those things tell you so much about so much. With the onslaught of multiport fuel injection, it's my experience that dodge 5.2/5.9 timing chains are just about indestructible, barring racing, heavy duty towing/hauling or simple negligence of oil change cycles. My next question would then be, have you ever replaced your crank sensor? If so, is it a mopar?

 

Can you see the IAC value? If so what is it? Pull that up and TPS give it a quick rev and see what they do