what do you guys think...when the truck is at idle (warmed up all the way) my temp gauge will go front the normal 195 to about 230ish, then when i rev the engine to 1500 rpm or take it for a little drive, the temp drops right back 195 until i start to idle again. when the engine goes above 195, my heat is gone inside the truck as well until i give it some gas then the heat will come back. i am thinking its the thermostat, being 12 years old and original it is probably going bad, but what do you guys think?

 

Sounds more like you have a problem with air flow through the radiator. Could be a clogged radiator (bugs, road debris, etc) or an out of place fan shroud. When you are not moving, the fan is all that is pulling air through the radiator. If the fan shroud is not in the proper position or is broken, it will effect cooling at low speeds. Rev the engine or drive down the road and you increase the airflow through the radiator.

 

thanks, ill look at it today