Check simple stuff first, air filter OK? Spark plugs? Petcock and filter? Any air leaks around the boots(spray a little carb cleaner around the boots when it´s idling and see if the idle speed changes, actually propane works better)? We might need more info. How does it run below that? Idle OK and what rpm? How´s the throttle response? When it wants to stall, is it spitting or missing or just dying out? Any smoke?