[jhv48]

Pull all the plugs and clean them.

Reinstall and try again.

You have a fuel issue. If the floats are properly filled and not leaking, it should fire right up and clean up when warm.

If they foul out again, and they are getting spark, drain fuel tank, lines and float bowls, clean plugs again and then fill the tank with fresh fuel. Prime carb and then monitor fuel pressure to make sure it is not over powering the floats. Look into the carb throat using a mirror so your face isn't over the carb. Have someone crank the starter for you while you watch for excess fuel flowing into the manifold. Should fire right up and run right!

The only variable was the fuel additive. Probably the culprit!