Replaced the seat and seal. Put everything back on and fired up tonight. At idle the engine stalls out. When I apply a little throttle, revs to high to put in gear. Needs to be in gear while engine is off to drive now. Start up and take off, runs strong - better then before. Let the gas off and engine stalls out again. I only drove for a couple minutes - could air still be in the system? Also backfires when engine cuts off. This was not a problem before. What is causing the lean condition? How do you tell if the float level is not correct? Looked fine when I put everything back together.