Reread Zed1015’s post. He is saying to fine tune the adjustments on the carburetors.
Have you checked the fuel level in each carb using the clear tube method? Setting float heights dry will only get you close, but not exactly where it needs to be. The fuel level needs to be spot on before proceeding with other adjustments.
Then carefully fine tune the pilot screws. A small adjustment can make a big difference, and it is likely that each carburetor will need a slightly different setting.
After these adjustments are done, then synchronize the carburetors.
Readjust the idle speed as needed after each other adjustment.
These steps have to be done in this order. If you cannot get a step dialed in properly, do not move to the next step thinking it will fix things. It will not. As Zed also wrote, there are many possibilities, so if these adjustments do not solve the problem, these other possibilities will need to be checked. Yes, it would have been easier to check them while the carburetors were off, but as long as they are on, it seems reasonable to try the adjustments.
Edit: I am referring to his post before last.