Tecumseh power problem

My Weedeater 42" riding mower has been giving a lack of power (stalling, governor hunting) at full throttle, especially under load. Problem is sporadic, but exasperating. I've serviced the carb on the Tecumseh OHV17 engine, cleaned the tank, new filters and fuel. any ideas?

when you say you "serviced the carb"
(what exactly did you do to it?)