Refer to post #2. Did you do ALL of those things? There is more to a tune up than just changing spark plugs.
When was the last time you changed:
Dist cap and rotor
plug wires
drained the bowl on the carb
What plugs are in it? Are they the correct ones?
Did you check the timing?
When the governor start trying to give the engine more throttle, does it open the carb all the way?
Need more info.
