I just bought an 89 bronco with only 82k original miles..Other than the fact that it's underpowered it runs great. The only thing I noticed is the temp gauge seems to be normal when it's straight up and down. But as I'm going down the road it will drop down a 1/4 inch and then go up a 1/4 inch above normal. It happens pretty quickly you can watch the gauge go up and down. Is this common? I don't seem to be losing any coolant, but every car that has ever done this to me has had a headgasket issue....I dunno...What do you guys think?