The Idle Air Control valve located in the throttle body.
The spark plug gap can cause the RPMs to fluctuate, while idling. The more probable cause of the fluctuating RPMs is a bad camshaft.
It could stall if you use the rear brake while going downhill. Is this the case?
You have a vacuum leak at the intake.
When a vehicle is idling, the engine may not produce enough heat to warm the coolant effectively, leading to cold air from the heater. In contrast, while driving, the engine works harder and generates more heat, allowing the heater to blow warm air. The engine temperature can rise while idling due to reduced airflow through the radiator and less coolant circulation, while driving increases airflow and coolant flow, helping to cool the engine.
Engine bounce is a phenomenon where the engine speed rises rapidly and then drops back down while the vehicle is idling. This can be caused by issues with the fuel system, ignition system, or engine timing. It can lead to rough idling and poor engine performance.
It depends on how long you are idling, or how fast you are going. If you know you are going to be idling for a long time, it's best just to put your car in park.
Have your sensors checked.
check your coolant level.
How to fold down rear seats in 1998 Saturn
If you land on Saturn you might sink down and fall.
set the idle down on the carb
It is more than likely a thermostat