Every time I change spark plugs which is often one of the spark plugs is fouled out on the left cylinder, it ran great until I inadvertently put in old gas have since put on a ne carb, new fuel pump, an gas additive because according to the local John Deer gas with alcohol clabbers up the carb. It also blows out a grey smoke,

Hi,
Just a question, is it the right hand cylinder of a Kawasaki V-twin? I think it is and that means it is a clogged air filter. Visual examination will not reveal this; can look pretty clean and still be too clogged.
These Kawasaki engines have the air requirements clearly defined by the engineers and for some reason it is the right cylinder that is most susceptible.
Peace,
Clarke