weber carb

have a toyota 20r with a weber carb that a friend of mine gave me and said it needed to be cleaned out. I cleaned everything in it but the problem is the motor wont rev without spitting and trying to die. I have adjusted the mixture and idle but didnt help. if you close the choke butterfly almost all the way it will rev decent. this happens when cold or hot. this is one thing on the side of the carb facing the valve cover with a seal saying removal will void the warranty. is there something under that seal that might be causing this.

Might be too much carburetor for the engine, try jetting it down.