When rebuilding or cleaning the carb VERY special attention need to be paid to the "emulsion well" seal. The emulsion well is in the center of the bowl and seals with the bowl gasket. If and many are the bowl halves are not pristine this seal in the center does not seal
. Any leak will have adverse affects on fuel delivery especially making the mix lean at idle and even full throttle. It is a must that the gasket seals in the "center".
Dave Neptune