Ditto on the ignition system, particularly the distributor. Ford products during those years used a "vacu-matic" advance system that used venturi vacuum measured in inches of water for spark advance. (no centrifugal advance) It required a special water manometer on the Sun distributor tester to check one out, and our family shop had the only one in Nashville for a while, including the Ford dealers! A small leak at the vacuum diaphragm would result in NO spark advance.

Another problem involves the distributoirs' bad habit of wearing out the upper bushing in the housing, making it impossible to maintain a steady point gap or dwell setting. Either one of these problems, vacuum advance of dwell variation, will cause the symptoms you're experiencing.
Jerry

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