power loss on 2 stroke

If anyone remembers, I had a problem with my carb leaking. Well I swapped out my carburetor with what was supposed to be a "parts" carb. No more leaks but my power was cut in at least half. Now I lose speed even on the smallest hills. I tried a new spark plug today. I checked my prongs in the carburetor and they have full range of motion with no sticking.

Anyone have any ideas? I'm at a loss. I appreciate any help.

cd

The old plug was black.

Thanks man... I'm working on that now... will let you know what happens.