Last weekend, while riding my buddies sled, the thing started to sputter/miss BAD after 7K RPMS. Wouldn't go above 55-60mph. We stopped, and I threw in a new set of plugs, which seemed to cure it for a while. We didn't get more than 10 miles down the trail and it starts it again. It'll run perfect at idle and all the way up to 7K, but after that its like its pumpin a dead cylinder. We tried new plugs again, and swapped the plug wires side to side, which didn't seem to make a difference. I'm going to try swapping coils, but from what I've read and know, this seems likely a stator failure. Another thing was it was a pretty warm day when this was acting up.... Any thoughts? TIA!