i have a mahindra c27 i purchased new10 months ago.it has never ran out of fuel .it has 98 hrs on meter.i was useing it to clear some small trees on my place . when i parked the tractor it was running fine.we had a cold spell 10 degrees. it has warmed up with lows in 40s highs in 50s. fuel was winter treated. now tractor will start but acts like its only running on one cylinder . it has black smoke comeing from exhaust.wwhen i try to give it throttle the engine neither speeds up or slows down . please help