I have a 2001 Cavalier with a 2.2l and a 5 speed. When I was driving it today I noticed when I push in the clutch and my foot is off the throttle the rpms will increase or hang for a few seconds then drop. I am thinking it may be an idle air control valve that is hanging up. Just to give an example when I shift at 3000 rpm the rpm will stay at 3000 or raise up a few hundred before going down to idle. I have also tried pushing the clutch pedal down while coasting and every time I push the pedal down the rpms will raise up and hang for a few seconds then idle back down. It is almost like I have an air leak but I have no check engine light on.