I just purchased a kitfox model 3 with grey head 582. Engine has 190 hrs. I have no experience with this airplane or rotax engines. I have been seeing EGT'S. At 1250 in cruise rpm of 5800. I have read this is to high so I decided to raise the needle one position to make it richer. Flew it and it climbed out smooth with full throttle but from 4 to 6 thousand rpm it misses and shutters pretty bad. The EGT'S where down around 1100 though. So I moved the needles back to where they were and it runs like it did before, smooth but EGT'S at 1250. What should I do or check. I'm lost.