1985 Volkswagen Van intermittant ignition problem

The car would die suddenly and finally would not start up again. Fianally pinpointed a faulty Hall Sender inside the distributor and replaced it. Now it will intermittantly act much the same way as before--like someone reached over and turned the key off while the car is running--except it is only briefly, sometimes just feels like a split second--the car will just jerk. It's been doing this for over a year and has yet to leave us stranded, but I would like to be able to totally trust it won't do that. What parts of the ignition system could cause momentary total loss of power? How can I isolate the part so I can fix it?

Thanks

Roger