Full Size Jeep Network

I am having issues with the idle. On cold start the RPM immediately jumps to 1700 RPM and stays there even after the engine warms up, I have to shut it off and after the restart it and then it idles properly at 750 RPM. When coming to a stop after driving the idle hangs up a 1200 RPM and I have to shut it off again and restart to get it to idle at 750 RPM. I have run a Winaldl program on it and all the readings are good so it's not a fuel issue and the fuel pressure in good and consistent at 12psi. It's not the PROM programing because I already had to have that reprogrammed because it was running too lean and I was having the idle issues before the PROM was reprogrammed. Any ideas on what to look at next? Thanks

A sticking idle air control would be my guess. Never had your described issue but there are only a couple of thing that could cause that. One thing to remember, programming doesn’t change on its own beyond some self learning, with TBI that is very limited and most set ups are limited to fuel trimming based on O2 data, so I wouldn’t even give that a second thought.

Unplug the IAC and see if the issue changes. When I had an idle air control valve fail on my XJ, I had to drive with it unplugged until a new one came in. It won't run great, but it at least prevented the idle from going all over the place.

The IAC plug is on the passenger rear side of the TB as I recall for those GM units.