I have the Can Am Alpine Flex Plow, best plow out there, super easy to hook up and take off by pressing the foot pedal. The springs are heavy duty so you can push a lot more snow than your standard steel blade. Well worth the money!
Mine would backfire too after I would run full throttle or a hard pull without idling for a bit....let 'er calm down for a little bit before hitting the kill switch.
I think it is a knock sensor failure...could it possibly have had bad gas in it? or stale gas? Has the ECU been replaced? I think the ECU's were updated to take care of that code.