I was riding today in temps of 12-16 degrees with -30 windchills and my sled ran really good, but after 40 or so miles it started to idle really high, like at clutch engagement speed. I stopped once to let others catch up and the sled died and would not start. It will fire, but not stay running. Any ideas? Smart valves, etc.? I'm stumped and need to get it going by Friday.