Will not idle

I have a 99 Grand Prix GTP. car will not idle at all. Runs great while driving down the road normal or even when you get on the gas hard. There is no hesitation, the rpm's do not bounce, nothing except when you let off the gas to stop it will not try to idle at all, just dies. I checked the sprak plugs and wires already they are fine and since it runs great while driving I am not sure where to start looking.

Remove the idle air control motor on the side of the throttle body and clean it with throttle body cleaner. Don't move the pintle while you have it out just spray it off well. Then clean the hole where the IAC goes in to the throttle body. Replace it and then start the car. It will idle poorly and then it should pick up. You may also want to use some fuel injector cleaner in the tank and then see what happens. You may be to the point where you will need to remove and clean the throttle body as well. Also change the PCV valve on the car if it hasn't been changed lately. It could be plugged or sticking.

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