try cleaning the IAC motor out well, it can get gummy. also clean the throttle body, the IAC passages, and if none of that helps check for the throttle cable being too tight/not releasing or the TPS being misadjusted.
it's directly under the throttle body, it has an electrical connector plugged into it. to take it out u need to remove the entire throttle body assembly. try cleaning it first though before u dive into taking it out. if u spray too much throttle body cleaner into the throttle body at once the engine will be hard to start when u try to turn the car on. jusy spray small amounts at a time into the diamond shaped hole inside the throttle body and clean the throttle bore real good too. if its hard to start when u turn it on just give it a little gas and u should be ok.where is the IAC located at? and is it pretty easy to get to so I can take it off to clean it out?