Hi everyone, I have a 66 mustang coupe that I have a problem with the temp gauge. When I drive the car a couple miles the gauge goes all the way to H. I have measured the temp of the engine it it's about 170 / 180 degrees after driving about 1/2 hour or so. I have replaced the sensor as well as all the wiringand the thermostat . When the needle starts moving it not a fluid motion. At this point I'm at a loss. Any suggestions would be greatly appreciated.