Is my coil to blame???

A coil getting too hot can do that. I found out when I jumpered +12V straight to the factory coil of my 64 Valiant when driving it home the first time, since the ignition switch was acting up. Ran fine for 5 min, then missed at wider throttle. Did you try touching your coil? Mine was real hot. Jumpered in the ballast and drove home fine.