I have a 99 Expy that has always run well (95k miles). Recently it has stalled on a couple occaisions and would not hold an idle...with no service lights etc. I had thought that since this was immediately following or during heavy rains that I probably just got some water in the intake, as it has one of those AIRAID open cone intakes (from previous owner) and after running it around town for a while it would idle up and run fine.

well it did it again this morning after being parked in the (dry as a bone) garage overnight (and not wet for days). No service lights, and runs reasonably smooth and seems fine otherwise just will not idle! (will actually hold a 400rpm idle if you baby the throttle there but will otherwise just stall under normal driving conditions)

Questions:
could it be getting a readable error code with no SES lights?

was assuming idle was computer or sensor (MAF?) controlled...no way to manually bring up the idle right? (it does seem to run fine otherwise)

best way to track down? I was thinking something like the MAF sensor might be bad or dirty, but I do hear about water leaks and electronic issues on these trucks......how do I determin where to start? If i drive it to a mechanic, by the time I get there it will probably be idling fine by then.

I can't let the wife drive it til I figure this out. HELP please!

 

Clean or replace the IAC valve.

Reset the PCM's KAM.

Steve