Alright so 3 years ago i was riding my dads 1997 polaris trail to school when it suddenly started to bog, i thought i saw something come off the sled but could not find anything. The Sled would not move under its own power and would not idle right. Got it home and took the carbs apart cleaned them and put them together, still did the same thing, if the air box is off it will idle but still not move under its own power. Lifting it solves the moving problem the track will spin easy. it has good compression it was one of the first things we checked. we swapped carbs and that did not work. we have checked to see if anything is preventing it to move when on the ground but nothing. this problem has had me, my dad, and my friends quite stumped. any help would be awesome.