i have a 98 sportsman 500 with 2100 miles on it. problem is took it for a ride, rode great for the first few miles, now it idles perfect but soon as you try to give it gas it wants to stall out, let off the gas and idles perfect, i got it up to 10 mph by feathering the throttle and got going down a hill and it took off and ran good for a mile and back fired couple times and started doing the same thing, could these be in the throttle contol switch on handle bar, i did put gas in it before i took of on it, maybe some in the carb? any help woould be great! thanks