My dad had a 76 Dodge pickup we went through this process with many years ago. I think he replaced nearly everything on the truck searching for the cause. In our case, the wire terminal to the coil had all be a few wire strands that were broken. Installed both new terminals on the coil and he never had a problem again.

My advice? Carefully look the engine wiring harness over real good, starting at the bulkhead connector. Check every connection, if any connection looks even a little doubtful, change it. A little corrosion here and a little there add up to a problem at some point. Gene