I own a 2004 900 stx ski and it runs great for up to 20-30 min then it starts to bogg like the ignition is bieng shut down for a split second then comes right back to full power. I t does not do it at half thottle settings or when the ski is cool. I check for fuel contamination none found. does it sound like at high temp something in the ignition curcuit is breaking down not giving it spark.. please help.