Q: 2004 mitsubishi endeavor overheating while driving, cools while idling or in traffic

Based on your description it sounds like the overheating is accompanied by a coolant leak. Coolant leaks can be either a cause OR a consequence of overheating. Be sure not to drive the car if it is overheating because overheating can warp the cylinder head and/or engine block causing costly damage. 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. An important thing to keep in mind is once an engine has overheated, you should replace your engine cooling thermostat because episodes of overheating can damage the thermostat. If the thermostat is damaged, and left in place, that can set the stage for future cooling system problems. 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. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.