Do you know where the heat riser tube is located? I've never heard of this before, will try to do a search on it. We've owned the van since new, in the same climate, but only recently started do this after about 25 years of being on the road.

 

Educated myself a bit on heat risers. Can't find any on the exhaust manifold.

 

You won't have one, as your van isn't carbed.

You already replaced the IAC with a genuine mopar part, right? Did you clean the IAC well REALLY ..... well..... when you changed it? Did you reset the PCM afterwards?

If you have a scanner that can read live data, think I would look at what the PCM thought engine temp, and intake air temp were when it is stalling. See if the numbers bear in resemblance to reality.

 

If you have a round air cleaner, there will be a short tube on the bottom of the snout. S flexible metal tube will run down from that to the exhaust manifold. I ran into issues with it on my '93 GMC when I put headers on it as there's no place to attach it. Mine just hangs down but it did a decent job in single digit temperatures. If you have the later cap style on the TBI, you won't have one as the filter is on the side.

 

I first replaced with a "Standard" brand part, and then recently a used Mopar IAC (since I can't find them new). No change. I removed the entire throttle body, cleaned with Throttle Body Cleaner and brushed away all of the black gunk. It was really dirty. Made sure to clean every bit off and even the tiny air passages. Reinstalled with a new gasket, and there was no change. PCM was reset with between changes by disconnecting battery.

I also bought a MT2500 specifically to fix this issue, so I have that to view live data. The intake air temp and coolant temp readings seem to be accurate.

The Short-Term fuel trim seems to be jumping quickly, ranging down to -14 and up to +8. Long-term is at 0 currently (because of the battery disconnect), but it did set to -4.4 for a few seconds, then to 0, then to +2 for another min, back down to 0.

 

Might try doing a relearn.... disconnect the battery, turn on the headlights for a few seconds, turn off the headlights, hook the battery back up, turn the key to "On", (not start) count to ten, then start the van. (don't touch anything.) That will give the PCM the chance to relearn the zero values on various sensors...... PCM should figure out idle pretty quick. (I try and do it on a cold engine..... not sure if it really matters.)

 

I do remember seeing this procedure on a different post on here, and I did do it previously. I did it this morning, one more time just in case. You can see the pintle on the IAC moving out/in when the key is first turned. But still no change with the stalling.

 

Have you checked fuel pressure?

 

Yes. Fuel pressure is at 39 psi with key on and at idle.

 

Well, that's correct. Don't suppose you have a scanner that is capable of graphing data by any chance? There are just too many possibilities for your particular symptoms.....