coldrunning moter

my car runs at normal temp when running 65mph or slower but if irun faster the engine cools down and heater starts blowing cold air

have you tried flushing the coolant system and how long has it been since you changed thermostat? also look at your radiator cap to see if you need new one or you could put hotter thermo in it....good luck....

I had the same issue with my car. I replaced the stat and flushed the coolant, got better.I had to block 90% of my radiator to get the car to heat up.Never over heated the motor and the heat work wonderful. Try that.