High octane fuel is not richer. It still uses the exact same jets as regular octane fuel. The only thing high octane means is more knock resistance, hence potentially can take more spark advance.

It's not generally cleaner either (does not have more cleaning additives). But if the fuel station puts one or the other in comtaminated tanks it will be a problem.

The reason for "running bad and bogging down, hard to start, and really back firey" is most commonly caused by clogged jets. Easy to clean with a Hitachi, but more tricky with a weber. You have to remove the Weber, remove the top and dump the fuel out and spray the passages. Or you could try this: leave the weber on the engine, remove the top and suck out the existing fuel with a cooking baster. Then remove the jets and suck the passages below the jets too.