I own a 91DX with a B16 and S1 tranny which I recently drove the car from Arizona to Missouri. First, I was driving through Ft. Worth TX when my temperature gauge slowly began to drop, it would move back up the more revs I threw on it. It was up or down for a while. I would go back up to normal when I stopped. Eventually it got to the point where it would stay in the cold range when I was moving, but when I stopped it went back up to normal. The radiator was cool to the touch and the motor itself was warm/hot. The only thing I can think of was because it was so cold outside that the air on the radiator at 80mph caused a super cooling effect. Does anyone have any ideas as to what this could be? Secondly, my car likes to develop a miss/hesitation/studder while crusing at a constant speed. This isnt all the time, just every now and then....mainly on the freeway. The exhaust makes a burbling sound and you can feel the car hesitating. If the gas pedal is held steady it jumps onto acceleration and off again. If you press the gas pedal to accelerate the problem seems to go away. The first time this happened I reset the ECU and it seemed to cure the problem. The last two times it has gone away on its own. I have no idea what could be causing it...if anyone has any idea help would be appreciated. Sorry for the super long post.

 

Is your coolant level low? Could be air in the system that causes the temp gauge to misread. The air would also throw off the TW sensor making the ECU think the engine is cold and delivering too much fuel.