Recently my girlfriend just had a mini-me swap done on her car (it is a 93 ex couple with a d15b7 swap in it). The reason we had done this to the car besides better performance was that the head gasket had blown on the motor. So we had a mechanic do the swap, along with adding new parts just as a new water pump, timing belt, and other things that it needed. Well when we got the car back, it ran beautifully. However we noticed that the faster you go, the more the temperature increases. Also once the temp goes up, it jumps around really fast but if you continue to go fast it eventually will overheat. If she drives like under 45mph, it doesnt over heat. The thermostat is brand new and works, as do the electric fans (not that it would help the car much at 70+mph. Anyone have any idea what the problem could be? and help is greatly appreciated.