Q: So when I'm sitting still in my Chrysler Sebring 2004 the car starts to run hot but when I drive it cools back down

The overheating at idle is typically due to a marginal cooling system and/or malfunctioning radiator cooling fans. When the vehicle is moving the extra airflow masks an overheating problem. When you are stopped, the airflow is less and overheating becomes more obvious. The most common causes of overheating include low coolant level (including that due to leaks), a faulty thermostat, a plugged radiator, a faulty radiator pressure cap, collapsed hoses, non functioning cooling fans, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket, poor engine running condition or exhaust blockages can also cause overheating. If you desire that this overheating problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you. With regard to the fluctuation in engine RPM, that can be due to a faulty idle air control valve or circuit (IAC), a faulty ECM (not common), faults in the fuel pump control circuit, defective spark plug(s) or ignition system components, faulty fuel injector(s) or injector circuit faults, and PCV system faults. Often, the application of a real time automotive scanner can find the fault as actual engine operating parameters can be viewed during the erratic operation. I would recommend that you request a rough operation/rough idle diagnostic and the responding certified mechanic will perform the required diagnostic steps to get this resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.