My suspicions are still ignition irregularities.
Lets prove/disprove it by observing spark strength/regularity.
Pull the coil high voltage lead from the distributor with the engine running and quickly, so it doesn't die,hold the end close to the dist socket so the spark can be observed as it goes to the dist rotor.
Bring the engine speed up to the point where the popping /missing starts-- observing the spark it should: be regular--be strong enough to jump a gap of 1/2 inch.Move the wire to open the gap to the point of misfire/stall and see how far it can jump.
Weak or intermittant spark can be a bad coil wire or point spring broken, loose condensor, dist-coil primary wire problem, cond wire problem, dist internal ground wire problem,POINT GAP closed, dist not well grounded and maybe someone can fill in some blanks.I have experienced all the above.
I don't think a cap/rotor problem would allow smooth idle and lood low speed performance.
You didn't mention if the choke had any effect on the off idle running.
Don't guess-test.
