I have a 2004 Grizzly 660. After riding at slow steady speeds in nasty terain that requires 4X4 my gas usually boils (but not always) and when I come to a hill and need to give it some gas it starts to cut out bad. It was so bad this last ride I couldn't climb a hill that my sons 80cc climbed. Usually I'll have to lket it cool down and slowly work myself back and forth up the hill until everything "clears" out and then it will rip up the hill. At first I thought it had to do with incline, but even on a straight stretch under those conditions it will cut out (when I get on the gas). It acts like it's loading up and once I've cleared it out it will be fine for a few more miles. Any ideas?