Originally Posted by bradb
why whould he be in deep shit? if the fans cut on and it still over heating more then likey its the thermostat and that only takes like 15 minutes to put iton an the part is like 15 bucks.
Re-read what OP is saying. His temp gauge is showing the engine overheating while idling but good while driving. What does that mean? That coolant must be circulating through the radiator and is getting cooled down by the headwind. If the thermostat was indeed stuck shut then your engine will not be cooling down at any time - except when the cooling fans were running. In which case you'll have what is called an "engine running too hot" condition.
Now keep in mind that our temp gauge does not work linearly. It will sit in the midrange point even while the engine is burning up. Luckily an engine coolant temperature sensor is sensing the actual coolant temperature and feeding that over to the ECU. If the ECU senses about 203 degrees F it should turn on the cooling fans while the water temp gauge remains at midrange. So, are the fans kicking ON? If not, then either the water temp gauge is lying or the cooling fan circuit has a problem. One way to test that, and to also keep the engine cooled off some, is to turn the AC switch ON. And if that still hasn't caused the fans to come ON then he is indeed in deep caca. I'm more inclined to think though that the temp gauge is lying. But OP hasn't responded to confirm.