So my 1988 caravan with the 2.5L and a 5 speed stalls very predictably at idle after about 45 seconds or so and starts right back up with just a bump of the starter. The IAC motor looks almost new, the throttle body is clean, there don't seem to be any glaring vacuum leaks and I just tried the test where you pull the connector off the throttle position sensor and it acts exactly the same way. When the air cleaner is off and you look down the throttle body at idle, there is a mist of fuel being spray onto the closed throttle body butterfly, and after about 45 seconds, the airflow sound increases dramatically, until the engine quits What do the experts have to say?

 

Don't confuse a new looking sensor for a good sensor. I went through 3 IACs before I actually got a good one.

Check for play in your throttle shaft, also had this cause a similar issue.

 

If there's play in the throttle shaft, then what?

 

In my case it was allowing the throttle plate to seal completely, which would cause the engine to die. Some air is supposed to get around the throttle plate at idle (closed), the IAC controls how much extra it needs to keep running, if the plate is able to seal, the vacuum can cause it to seal suddenly at idle, which the IAC cannot account for quick enough.

I fought this issue for a while, changing sensors (thank god for having spare parts), checking wiring, never getting a code.

I'm guessing this is only an idle issue, and it runs fine when driving otherwise.

 

Yes, only an idle issue. The thing is, half the time it will get to a chugging, barely idling state, (like 400 rpm or less)then suddenly pick up, accelerate significantly and idle fine for a little while, then repeat the whole process, if it doesn't just outright die.

 

I would check the IAC then. Chances are its not responding quick enough which could be caused by a number of things. The IAC uses vacuum reading from the MAP, and TPS readings to adjust, so one of these could be faulty. Could be faulty wiring to the IAC.

My car was giving me a lot of sensor issues recently, so I went through and cleaned/greased all my underhood connections and checked all my vacuum lines, so far I have not had anymore issues.