The fluctuations are immediate in that it gradually moves from 1/2 way mark to cold and then gradually moves back up to 1/2 way mark. Right about the time when it starts going down I do hear the cooling fans kick in and the rpm gauge becomes hypersensitive (goes down toward 1000 when i lift my foot off the gas and when i step on the gas remains higher than it should). could you describe in detail the steps i need to follow to flush the air out of the system?