I have a 2002 Arctic Cat ZR600 that just doesn't want to run above idle. I give it gas and it backfires, spits, and sputters then finally will go at WOT, but then as soon as you let off the gas, it dies. after it is warm, it wont run above idle at all, you give it gas and it bogs down terribly and backfires then eventually dies. it has spark in both cylinders. anything commonly go wrong on these sleds? it only has 2100 miles. any input would be greatly appreciated! thanks