There are a few threads in the forum discussing PTO problems and possible solutions...mainly voltage needs to be checked and PTO has to be adjusted correctly. For the surging problem, you may have a fuel line restricted or partially plugged, carb could be dirty (main jets) or lastly the governor may have a problem. I'd start with the easy stuff before messing with the governor, though. Sometimes it's worth draining the gas tank, replacing all the old fuel lines, cleaning the carb, and starting from there. Also clean out the gas tank....
Rattosh51
YT6800