I replaced the air flow sensor about 6 weeks ago. My Monte Carlo was stalling, not starting and acting crazy. The part fixed the car and it has ran perfect since then. It even got rid of my check engine light. Well last night I noticed my car was revving really low when at a red light or slowing down. It's at about 200- 300 rpm's now when I am parked. It drives fine though, no missing or stalling. Should I be worried about this? I didn't think it was supposed to rev so low. Like I said its driving fine and starting fine, just concerned. It's a 2005 SS supercharged if that makes a difference.