My Sl900 runs great at full speed and then all of a sudden it bogs down to almost an idle. When I give it the gas it doesn't have any power and the ski moves slowly. I keep trying to go and then all of a sudden full power returns and away I go. Runs for about 1-2 min then does it again. I finally made it back to my truck doing this routine. It ran great for 2 days and this happened on the 3rd consecutive day out. Any Ideas?