Where do I start?

1964 Comet 289/C4

So I'm driving one day, and the Merc begins to cut out as if something electrical is going havoc. I get it home and through trial and error, I replace distributor, coil and wires with Pertronix and even replace the plugs.

Still getting issues but this time it's sluggish at excelleration. Figure it's jetting, but it ran fine before the cut out incident. I go off and replace the carb with a 600cfm Edelbrock and time her at 12 degrees. SHe starts like a champ, and at higher RPM, runs well. It's only at low roll on that I get an issue.

I replace the fuel pump... no fix. I'm almost sure it's electrical now, but with all the replacements (ALL the secondary circuits) I can't figure it out. I even replaced the pink ignition wire with a high grade line coing directly from the ignition to the positive side of the coil.

I don't know what else to check at this point. Any suggestions? Again, I doubt it's fuel, as the carb ran fine before she cut out that day.