This engine hadn't been used for a couple of years. The gas smelled rancid in the tank. I removed the carb and attempted to clean it. The carb was so gummed up I couldn't remove the main jet, so I bought a new carb. Installed the carb now the engine runs except for a surging at high throttle. The surge is not there at idle. I always thought that surging was a dirty carb, but this one is new. I drained all the old gas from the tank and changed the fuel filter before starting. I have done a static governor adjustment with no change. Does anyone have a suggestion as to why the engine is surging? Thanks for any help.