welcome, good chance its either the ignitor or rpm limitor or maybe both.......the rpm limitor is mounted against the front of engine below the carb......you have to look and the ignitor is in the same place but mounted to the back of the bracket that holds the limitor on.............the limitor is a black box aprox 2x2 inches......there is no way to bench test either one you have to replace with known good working parts.......but its not an uncommon problem on that year cart..........................
