I also had what I thought was a bad carb. I had to set the idle higher than it should be to keep the engine running at idle, and I also had a problem with the engine running rich based on the condition of the spark plugs. After fiddling with the carb, I finally checked the distributor. That's where the problem lay. The engine runs great now. At this point, I would check the dwell with a dwell meter instead of just a feeler gauge, make sure all wires are good by measuring the resistance from the cap to the spark plug end, and check the cap and rotor itself while you have it off. More likely a dwell or timing issue, but you might as well check the other items while your at it.
