Over heating problem

Okay so, about a week ago my car was overheating because, of a bad thermostat. So, I replaced the thermostat and put all new coolant into my car. The other night I got on the interstate and my temp gauge started to slowly creep towards hot. So, I took it out of gear and it dropped almost as fast as the RPMs. I ended up turning around and going home. I noticed the temp went up only on the highway. The temp did not rise when idleing or city driving. When the temp gauge would go down when it was "hot" when ever I would let off the gas or take it out of gear. I checked my coolant and it was fine. I also took my radiator cap off and squeezed the rubber tubing a bit to see if there was much air. Today I took it on the highway and went down just one exit. My car didn't overheat. It also has not overheated in hard city driving. Obviously there is no way my car can overheat in like 5 seconds and then cool down in just a few seconds. Any ideas as to what this could be?

Temperature sensor get fried?

that might be a problem, check that temperture connection. BTW if I saw my car over heat, I stop my car right away pop the hood, not turn around driving home like you :wink: .

No see my car would cool down to normal temp when ever I let off the gas. Trust me I didn't drive my car home all the way with the temp reading HOT. It only started to overheat when I would give it gas. As soon as I would let off the gas it would drop to normal temp.

Okay, so a friend says it is my head gasket. He says it probably has a very small leak and the coolant is getting sucked into the pistons after getting pressurized. He told me I should remove my thermostat untill I can get the head gasket replaced. Any one have some input on this?