I've got this '03 ozark 250 that revs up and starts up perfectly fine. The problem is, no matter how much throttle I give it it won't move. I've adjusted the philips head screw on it and it still won't move. The weirdest thing is that when starting it up after about an hour or so of it being off it rides for around 30 seconds and then it won't move again The brakes are good cause it moves in neutral. Don't know what it is.