Have a strange miss.

These cars were designed to have regular maintenance. You can't drive them for 5 years and do nothing. If they are new to you (meaning you didn't grow up with carbureted cars or anything older than late 80s) then you should know it will need the usual tune up stuff, cap, rotor, wires, plugs, fuel filter, plus the carb should be rebuilt and the whole thing tuned when that's all done. Better than factory parts will help it last some, especially good 8mm plug wires... but there are always limits and high powered ignitions will eat plugs, caps and rotors faster. Most cars back in the day would have been in for basic services that would have adjusted things and rebuilt/cleaned the carb at least once a year, and i recommend rebuilding any aftermarket carb at least once every two years if once a year is too much. It sounds like it needs just the basic maintenance.