Yours has the F engine which are the smoothest running one IMO. After watching some you tube vids, I've noticed about all of the Duraforce mowers run just like mine. It's highly recommended to put an in-line fuel shutoff, which I did today. The needle and seat prob need replaced to fix the flooding issue. Lots of Duraforce owners have the same issue of raw fuel being blown out of the exhaust on start-up. Lawn Boy must've gotten lazy in the last years by not having a fuel petcock like all the older mowers. It did however clean up pretty good.