Need help with 1992 90hp outboard engine

[swaps2]

I have a 1992 90hp Yamaha 2 stroke outboard engine, I have a problem with the engine not being able to achieve wide open throttle which is 5500 the highest I can reach i 4400 rpms. I have cleaned the carbs, changed cdi module, changed the plugs does anyone have suggestions of what else I can try? Any help would be appreciated.

[boats.net]

Check compression, check spark to see if firing on all cylinders and look for water on spark plugs. Check fuel diaphram to see if ruptured.