When I fire it up it idles fine, then I engage the blades and it takes a little longer than usual but they get up to speed. When I'm cutting is where the problem is. When I put a load on it it'll bog down and sometimes even spit a puff of black smoke. I took the bowl off the carb and it looked good. Changed the plugs, air filter and fuel filter and it still does the same thing. Even ran some Seafoam in it. Still got the same problem.