Where are you located?Back to 94 octane runs smooth. That should mean it is not dirt clogging the carb or jets - no?
How do I troubleshoot this?
Most places in the US, you can't GET 94 octane.
What kind of carb cleaner did you use ?
Get some Berrymans B12 Chemtool and run a tank at twice the recommendation; that would be 2 OZ per gallon, IIRC. While that is in the tank, open the drains and drain the float bowls once.
How's your idle speed; if it's too low it can contribute to low speed problems.
Have you attempted to adjust the low speed jets??
How long since the plugs were changed ?
Any major mods made.....exhaust.....air intake......heads, cams, etc. ??
If I were in your situation and the bike will just be used locally AND you continue to be able to get 94 octane gas........I'd be tempted to keep doing that and not worry about it.
Before resigning myself to that, however, I'd spend at least a little bit of time trying to run down the previous owner(s). Sounds to me like it might have been "juiced" and needs the extra octane.