Some times my car runs very fast other times it runs at like a nonturbo sppeeed.

My question is what kind of power loss do you see with heatsoak ,Because im not positive this is whats causing the inconsistancy in my cars power. and is it pretty drastic...Also would a new thermostat help the situation?? What else could I do other then fmic.

AS of write now my car is untuned with 1500 on rebuild. goes to get tuned in about 2-3 week. Im going to go ahead and get a new thermo. and see what happens after the tune?