Was cruising on an old highway when I punched it to pass a car. Once I hit 5000 rpm it kinda stopped going and my temp went way up. I kept going and it didn't have problems next time I wrapped it up pass 5000rpm but my temp gauge started getting dangerously high. Oddly the car was running fine again. So I turned the heat on to see if I was out of coolant or the thermostat went bad and hot air as usual. But soon after the temp dropped to right below normal. What the hell happened?

 

Thermostat stuck???

 

your clutch fan is shot...thermostats go out(brake) in the wide open position and leave the car runnin too cool....you can tst the thermostat really easy..takeit out..boil soem water andpuit it in..if it opens when put int he water then you are OK...99.9% bet its the clutch fan

 

Sounds like time for an electric fan.