[RichardJ]

Never a good idea to introduce a new variable when trying to troubleshoot a problem.

A year ago you had questions about doing a tune up. You were advised to find a Dwell Meter rather than rely on setting the gap manually. A year later the points are possibly corroded, pitted and in need of cleaning and readjusted. File with small metal file.

After point adjustment, check and reset timing.

Spray carb cleaner around intake manifold while running and check for vacuum leak.