Kawasaki running bad.............

[wanabe]

I have a 19 hp kawasaki v twin that recently started not running right. At idle it runs/sonds ok. But at full throttle it sounds like it has a very slight mis fire. When this motor has a load put on it, it smokes black bad and has less power than it did before. Any ideas? Its in a Dixon zero turn if it matters. We cleaned the air filter, and put a new fuel filter on it but did not help. Thanks

[Restrorob]

While it's running pull each plug wire one at a time (with rubber handled pliers) and see if it shuts off, If it does the coil on the opposite side isn't firing and needs replaced.

In other words, It sounds like it's only running on one cylinder.....