Ok, at my wits end with this machine. It's my daughters 2005 Polaris 340 fan classic with 600 miles. Great little sled for her and runs great except every once in a while (usually once every weekend) while riding the thing it will suddenly fall on it's face and load up on gas real bad on one cylinder. So bad that changing the plug sometimes won't even fix it. You have to get off the machine, floor and push it untill it gets rolling and burns off all the extra gas. It has done this with several different people riding at several different riding conditions. I have rebuilt the carbs with new needle and seats, and jets and it still does it. HELP??