Okay, my temp gauge is posessed. Well, probably not, but it is broken. It reads accurately while cold, then once it warms up to op. temp, it keeps climbing, making me think I am overheating. Sometimes if I tap on the gauge cluster it jumps to normal and stays, other times it does nothing, other times it jumps back and forth. If I do nothing, it will tick back and forth rapidly and then settle back down to where it ought to be. When I park, after driving for a while, and get back in the car, it reads all the way at H for a few minutes, then jumps back down to normal. Do you think this is the gauge, sensor, sending unit, wiring, or something else? What would the procedure be for testing the various parts?