Need help/advice

2001 Saturn SL2. Shakes once and RPMs drop for a second but come back up.Only happens while in gear completely stopped or a slow rool with no throttle.Can only describe it as a studder. While driving is fine. Sometimes every 20-30 seconds while at a red light. Please help

Clean the throttle body.

Cleaning the throttle body is a good idea, the other may be either a TPS problem or a motor mount problem. While changing gears the mount may shift and the engine may lay upon the cradle for a brief moment causing the shudder feeling. You will always experience a change in RPM when moving the gear selector, the vehicle will compensate for the load by adjusting the RPM’s, a lazy TPS sensor could be an issue related to it. How is you maintenance??? An SL2 will run until it stops meaning stops dead, you may need to tune this vehicle to bring it back up.

Repotimfl: I see that a lot of Saturns develop head gasket problems (not related to this question), do SL2’s not have head gasket problems? Is it only SL1’s that get this problem?