I'm a homeowner with a Husqvarna IZ4821 zero turn mower with a 21 HP Kawasaki FH641V V-Twin engine. When I start it (it starts great) and drive without the blade engaged is does OK for power (not great, but OK), but when I engage the blade it REALLY bogs down and almost stalls. I have to go very slowly. The mower only has about 200 hours on it, and I've changed the oil and filter at least once a year. The air filter is good. The plugs don't appear to be fouled and the fuel filter is OK. I've had it in the shop for a "stuck float" that somehow let oil into the gas, and it hasn't run right since, power wise. He told me to put Seafoam in the gas to keep it from happening again. It doesn't burn oil or smoke when I run it. I've looking for suggestions as to what might be wrong, and what I can do to fix it.