I have a 2002 Sable with DOHC engine. It started idling fast. In park if you accelerate and let off it stops at about 1500 rpm for about 1 or 2 minutes before it drops to 1000 rpm. If you are driving it will cruise at 35mph without any petal.
Yes the check engine light is on now P1506 Idle air controller valve overspeed error. So I replaced the Idle air control valve, but this did not change the problem. I can try to clean the throttle body first.