Missing at high RPM's

seems like it could be fuel. Could be too rich. I know when i had my truck after 4000rpm it wouldn't really pull cuz the engine was being flooded with fuel. Also on a old Ferrari 330 12 cylinder on of the carbs afer 5000rpm was just pouring fuel due to a leak at the base of the carb.

easy way to check leaks is get a spray bottle full of water and have engine running. spray water around base of carb and intake and if rpms changes you know you have a leak.