Frank,

Why are you rebuilding the carb? What diagnostic tests lead you to
suspect the carb? Have you checked for vacuum leaks? It sounds like you're
running lean.
Get a can of carb cleaner. Start the engine and let it run for a minute
or two. Spray carb cleaner where the carb bolts to the head. Does the engine
stumble? If yes, then fix the leak. Spray the head gasket. Did the engine
stumble? Et c.
I doubt that you have bad gas or a bad filter but these are easy to
replace.

Dave M.