[ted]

Don't know the history on your carb but if the throttle blades have been removed from the shafts in the past, then you may want to pull the carb and check the following.

Looking at the carb while it's upside down, look through the carb bores at a light source with the throttle in the idle position and secondaries closed and insure that each pair of blades are open the same. If the secondary blades are unequal and likewise, if the primary blades are not open equal, then the blade screws will need to be loosened and the blades likewise shifted around so that equal air flow through each pair will be made.

Also insure that the idle transfer slots in the primary side are exposed with the carb in the idle position. If the primary transfer slots are not exposed or just barely (0.005" or less), then check to see if the secondary blades are possibly open too much. The secondary blades can be closed by adjusting them at the small slotted screw that is accessible only from the bottom of the carb. This will force the primary blades to open up more thus exposing more of the idle transfer slot and possibly better fuel delivery at idle. Be sure to leave some amount of load or adjustment against the secondary air gap adjustment as taking it all out can cause the secondaries to stick closed.

If the carb checks out, look for a vacuum leak. The thin paper gaskets under carbs can be misleading at times and my require replacement although they visually look okay.