Re: uneven power
I've had motors back a few years ago that took forever to run in & then were still somewhat weak (doing measurements showed that some trans ports were a bit lower than others from same factory), so I don;t use them anymore.
It does sound like you're too rich on yours tho, so I'd drop the needle right to the bottom and see what happens, then maybe lower the float level a bit also if it gets better. After that, I'd be looking at making or buying a new main jet.
Sometimes I sets and thinks, sometimes I jes sets.