I had a similar problem with a straight six Mustang. After checking timing, timing chain slack, points, cap , rotor, plugs, carburetor, etc, I decided to put the 56 year old condenser back in. Voila!
As I soon learned, you can't count on new parts to work - even right out of the box in many cases.
The brand new NGK condenser with less than 1500 miles on it failed. I have since installed one of Jon Goodman's 200,000 hour condensers on every single vehicle in my fleet (with the exception of the Ford pickups that have electronic ignition).
https://www.stovebolt.com/ubbthread...native-condenser-update.html#Post1388813
