This symptom is almost always either the points in the bottom of the
distributor or the wiring between it and the computer. I believe I gave you
the terminal numbers on the computer plug to check last time. Suggest you
pull up that message and check at the 3-point connection on the lower
distributor for a pulsating continuity between the center terminal and each
of the outboard terminals while cranking. If you get good pulsations to both
sides then check at the computer plug.

I have had a couple sets of those lower points that seemed all right when out
of the distributor but one of the pusher blocks was worn or broken so only
one side actually pulsed when it was installed. This seems to be a common
problem and you may have to get some new lower points. I've seen them on
ebay from time to time.
--
George Downs Bartlesville, Heart of the USA!