I had just bought this machine from my sister it has 84 miles and 6.4 hours on it. She bought it brand new and it has bin sitting for a while. I had takin it for a ride this weekend and when I give it a lot of throttle it spits and sputters and when I let off the throttle some it will still go but not like it should. when I put it in low it runs better but it will spit and sputter sometimes but it seems to run better in low gear. when I put it in reverse it revs high then low then high then low and so on and will barley move. But when I push the 4wd button it will back right up with no problem. I had changed the spark plug and added some fresh fuel with the little left over fuel in the tank. has anyone had this problem or know what to do???