My 95 12V has one small problem. After it warms up you can watch the temp gauge as your going down the road and it will roll slowly up to the red line but not quite, and then jump back down to 140 and slowly begin its rise again. I also hear what sounds like a waterfall near the heater core every know and then. It does not leak or overheat. If its a thermostat problem, than wher is the thermostat?