This Is for a 1992 Polaris 500 SP EFI so first let me say the carbs wont be the problem because Its a EFI. Which Is fuel InJected. Well then heres my problem last year when I was riding about thirty mph the sled would start bogging alot and when I gave It gas It would keep on bogging until It went to zero mph but when I gave It gas It would bearly move, and all It would constantly do, would be sit there and bog as If It couldnt move and kept bogging. If I tryed to Increase speed It would slowly Increase but at the same time the snowmobile would bog and then bog back down to zero mph. Well the only time It wouldnt bog was when I was going about sixty then It would ride normal. But If I went under that then the sled would sit and bog every second and wouldnt let me drive for ****. I replaced the plugs but the problem was still there It would Just sit and bog when I would try to give the sled gas and when I was riding the snowmobile would bog down to zero mph. Then.