We have a 2001 Saturn SL1 and it is idoling around 2000 rpmunless the AC is on and then it idols at 1200 rpm. We have scanned it with the OBD2 scanner and it came up with the following codes: P0133B - O2S slow response sensor, and a PO507B - high idol. It also had a missfire code but oncethe code was cleared it has not showed back up yet. Have taken different parts off of a compatible Saturn that was running good but has not made a difference. Changed parts - Throttle position sensor, idol air sensor, complete throttle body, coolant temperature sensor, new plugs and wires. If anyone can help get the idoling back to normal, please help. By the way, the car is a 5 speed.

Have you checked for vacuum leaks. That could cause a high IDLE. Also damaged connector ends or damage to the wiring harness. Doesnt matter if you change a sensor if its connector is damaged or the wires leading toor from are as well.Edited by: Low Saturn

single cam motor. check intake manifold gasket. the gasket usually folds between cyl 1 an 2. spray carb cleaner on gasket.