Was riding all day long in fairly deep powder with no problems and all of the sudden on one climb at the end of the day I lost almost all of the engine power, like it was shutting down, and of course got stuck. I let off the throttle and it came back to life. Climbed a 2nd hill ran fine, and 3rd hill lost power again. On the way back down the groomed trail I ran it up to 8200 a few times (of course there is not much load on the engine on the trail) but no problems. I did have the carb heaters on that day as an experiment, which I have never done, but really that shouldn't have mattered? Maybe a jet issue with the carb? Fuel pump? It's an 800 Ptek