I have a 94 Honda Civic LX 160,000 miles, my thermostat would goto to high and then as I press the gas the thermostat would go back down to normal. I recently replaced the radiator, and for about a week the thermostat stayed normal but now it is doing it again. I will drive for about 30 mins and everything is fine, then if I stop the thermostat goes to high, when I press the gas (most of the time not all the time) the thermostat goes back down to normal. The faster I am going the faster the termostat goes back to normal. What do you think it is?