You focused on the fuel system. George's comment about the air sensor plate needs checking out, as it regulates fuel intake. A pretty penny to change out the feul distributor, wasn't it?

But how about ignition? Have you checked the points, condenser, cap and wires? You might try replacing all of the above (it's cheaper than the fuel distributor! I once had a problem that only went away after replacing the condensor. When putting an engine under a load, all sorts of electrical gremlins appear. Bad plug wires can bog down a perfect idling engine!