I got gas at a crappy gas station and the miss started after that. this is Rebuilt engine with less that 10 hrs on it. Ill go along and then the Rpms drop about 2-300 then they will come back up and so on and so on. First thought was bad gas. I still put a bottle of water remover in it and put 15 gal of good gas in it. this jump in rps occurs at any speed. I removed the water seperator and dumped it into a bottle and didnt see any water. Help