My engines constantly surges (speeds up & slows down) while running, could this be caused by the electronic fuel management system?

My engine is one year old and the engine was drained of gas for the winter and ran fine during several mowings this spring, when mowing the last time I stopped for a few minutes and restarted and the surging started. I noticed the rod from the carb to the governor moves up & down constantly. If I pull one plug wire off the rod stops moving and the engine smooths out. I can do this to either plug wire with the same results. Put new fuel filter on (old one was not clogged) and this did not help. Also put on new air filter.