I bought a new zero turn mower with a Briggs 24 HP motor on it late last fall. It only has about 20 hours on it now. It ran perfect when I started it up this spring. After mowing my 3 acres, I turned off the PTO and the engine loped or was hunting. It runs perfect with the PTO engaged. Dealer said it was fuel related and not covered under warranty. Is there any "snake oil" treatment that can be added to the fuel to clean the carburator as it is being run? I would hate to pull the carb for a cleaning job if there is something that would clean it as it is being run. It is usable as it is now, but it does not idle smoothly.