Sounds like 2 problems.
I would say you have the base or initial timing set wrong and or / the distributor advance weights are sticking also.
Check the mechanical weights to be sure they move freely. Then Unhook the vacuum advance, set timing at 12-14 degrees, then be sure the engine speed is at 650 or less after you set the timing. If it is faster, then turn out the base Idle screw to slow it down and recheck the timing.
Also Is the accelerator pump squirting as the throttle is cracked open?
Are you sure the carb has the correct float setting?
Are the Idle air bleed screws at about 2 turns each?
Fact is stranger than Fiction