My GTP is over heating and I think it's the thermostat. I put a 180 degree fail safe thermostat in it and it locked open and it never got up to operating temperature after that. It got warm enough to read on the gauge but it never got to normal temp, but when it's in, it over heats in a couple miles of driving it. I have a couple of different thermostats that I have tried but it still over heats. Do you have any Ideas?