318 Engine stumble

Or the transfer circuits are too rich. But you said you blew out the air bleeds.

I would adjust the float up and down while you do the same thing and see if it changes; that float adjustment will effect the richness of the mixture out of the transfer slots.

Did the new distributor get in there? I'll keep saying.... it can be ignition too. The spark voltage needed to fire the compressed fuel-air mixture varies. You just may be in an operating region where the mixture it harder to fire, and a weak ignition will show up under those conditions.

Did you ever post the measured resistance value of the the ballast?