Further investigation based on leads I have received from all of you has
netted the following:

1.9L WB w/digifant (1987)
(note: tests performed per VW factory manual, page 28.39 for coil test,
page 28.43 for hall sender test and page 28.44 for control unit test)

Coil test: OK

Hall sender unit test: (in bottom of distributor) OK

Control unit test(EC, ECU): OK

However the problem still occurs as it has, speraticaly.
(2 incidences today)
I think these tests were intended to be used on a vehicle that isn't
running at all.

The trouble is I can't rely on the problem to persist long enough to test
the above. I will load up all the necessary gear and make a try of it.

Q: If you grab ahold of the hall sender jack coming off the bottom of the
distributor, should it be loose? I would think not, but wiggling it has no
effect on the problem.

Any new suggestions?