Hello, my problem is simple to describe. Lately my car temperature gauge fluctuates. When I start the car and drive it for a few minutes, the engine is cold but as it starts to warm up, it goes to the M in "Normal" then up and up to almost hot but then drops back down to the middle. But then it goes right back up right below hot. I've changed the thermostat. Does this have anything to do with that? Could it be I have the wrong thermostat in? There are no leaks and have checked the water pump, radiator and fans but can't find the problem. Does anyone know why the temperature gauge would do this?