Chevrolet Repair: Cold highway driving problem, radiator hoses, cold highway

Question
Had a problem with my 96 cavalier 2.2L for a long time now. Whenever I drive around town the engine temperature is prefectly fine. Soon as I drive >55mph, that's when my temperature gauge drops to the cold line. (And I do a lot of highway driving!) It will do this until I get off the highway, where the engine will warm back up. The temperature sensor is correct, because the coolant is cold upon stopping from the highway.

Things I've done: temperature sensor (old one was good), thermostats(6 of them) & gaskets, water pump, upper & lower radiator hoses, heater hoses, flushed twice & refilled with Dexcool. The IAT & ECT sensors are fine. What else could it possibly be? Gimme a list!


Answer
Hi Dan,  The thermostat controls engine temp and you have replaced it a number of times. Do you have good heat while driving on the highway? Tell me what you mean by the "coolant is cold" after highway driving.

Let me know !!!!

Have a Nice day   Mark