I have a 95 civic ex, the problem just started about two days ago. I started like normal, it started up fine for about 5 minutes then the engine kept reving up and down while it was parked, but not going higher than 2500 rpm. It would keep doing this untill the car finally warmed up which took at least 10-15 minutes. Then just today I noticed that my cars taking a little longer to heat up, plus now it's starting to overheat. I think it might be the thermostat but not sure. Anyone have any solutions?? The car has 170,000 miles no mods