have 3 toro 2 cycles and am dealing with on and off terrible surging with them... 2 are late 80's one of which one I cleaned the Carb/jets/etc and the surging stopped. My primary 2002 2 cycle model never had problems until early last year and I have not had a good "no surge week" in quite some time...I have tried spark plugs/Carb jet cleaning/ gov. spring/ fuel filter/ etc... If anyone has any tips or long term fixes your information would be greatly appreciating as every once in a while the mower won't cut any grass because of a load...some times the mower will work flawlessly until after 20 min.s of mowing and then start the constant RPM cycle... THANKS!