The temp gauge runs good in park, but goes to over heat while driving? It stays relatively even as long as the heat is on full blast. What needs to be fixed.

Hi gfannon ... The first thought that comes to mind is thermostat failure. In fact, if you have had the thermostat worked on or replaced recently though it may have been installed in reverse which would lead to this kind of behavior ... On the other hand my Hail-Mary, long-shot-out-of-left-field-in-the-dark suggestion would be to check the timing on the car. Retarded timing at high revs could contribute to higher temps in the engine ... I can't discount your theory about the head gasket completely either but you haven't supported it by reporting any of the other typical symptoms of such a problem either. Sounds like it's time to see a pro however. If it is a head gasket you want it fixed now (assuming you want the car around for a while) and cycling the head through repeated overheats does little for your relationship with your engine. Good luck!

THERMOSTAT. Fan/Blade. . Radiator "clogged", or fins blocked from air flow? May need replacement, or "rod out" to get the coolant flowing again. [Radiator treatments "may" help, but this sounds beyond that!] .. IF it now takes the heater to be on in order to keep the water temperature down, this suggests that the radiator/thermostat are at fault. [I had a truck that had a single-core radiator rather than the proper-specified 3-core radiator "since birth", so that needed a replacement--always get the largest that will fit. -Hope that helps.... .