Normally Kawasaki engines are known for lugging power. I mean I could normally engage the blades at low throttle no problem. Now it sputters and loses power. After I run it for 10 minutes mowing it gets worse to where I can not even mow with it. I've drained the fuel tanks, fuel filter, spark plugs, and just had the carb cleaned and reinstalled. It ran great for 10 minutes of mowing then it started losing power again. Seems to be worse after it warms up to running temps. Even after I disengage the blades it sputters until it reaches full rpm's. Clears up under no load at full throttle, but sputters bad when you go from an idle to full rpm's. Could I have a coil getting weak? What else should I check?