Mine did the same thing. Thought it was jetting problem, but rejetting never fixed problem. Turned out my plug caps were bad. Get an ohm meter and test your caps, should ohm out at 5000. Mine ohm in the millons. Your plug cap caps have resitors in them and they are a wear item, many people don't know that. Replaced mine with NGK caps from my local dealer for 2.95 each. Took her out and ran perfect.