850 stalls when slowing down to a light or in gear except when I disconnect the iac

[mescalinedreamz]

I installed a new idle air control valve hoping to fix it..both old valve and new check out fine. Anyways I can plug the idle air control valve in when the car is cold and it won't let me put it in reverse or drive without stalling..park and neutral I get a steady 1000 Rpms..when warm I can feather the gas and take off but not when cold. When slowing to a light I can stop and a second later the Rpms drop to zero.

Now with the idle air control valve disconnected it'll die from cold at idle in park or neutral until warmed up and then I can drive it normally but gas mileage suffers. So I usually warm it up with the iac plugged in and unplug it when warmed up..or else I keep the iac plugged in and throw it into neutral at every stoplight.

I'm thinking a sensor..maybe the temp sensor located under the thermostat..but not sure..gonna test it when cold and warm tomorrow. It's getting cold here in Ohio and it takes awhile to warm this thing up..thanks!

[RickHaleParker]

Leaks in the Air Intake.

[misha]

+1.
If it idles with iac disconnected it pulls air from somewhere else.
When iac is connected it have more air than needed and this choke the engine.

[mescalinedreamz]

Vacuum guage has never changed..always showed 19 at idle. I will try to spray the engine with choke cleaner hoping for a raise in idle.

[shegarty]

You'll want to check for unmetered air - so anything after the MAF. Check ALL of the intake hosing and associated clamps, you might need to smoke test the intercooler if you have a turbo setup.

[greg850r]

Order silicone lines and replace every vacuum line you can find. If they don't solve this problem it will head off your next one.