Given your diagnosis results, the issue must be in the distributor then.
i got one idea for you--just a guess:
Disconnect the ignition power transistor connector (ignition control module). Check the continuity between terminals 5 and 12 with the voltage applied and not applied. (You apply 1.5V to terminals 5 and 6 for the voltage applied portion of the test)
NOTE : An analog type ohmmeter should be used.
Replace the ignition power transistor if it is defective.
So looking at it, there are 6 terminals on the left, and two separate ones on the right. So # 5 is on the left, and you count 1 thru 6 starting fromt the left side.
# 12 is of course, the furthest right of the two on the right.
You might need to subscribe to ALLDATADIY
to get diagrams and more info. I can't fit it into this little box, sorry.
Or you could just take a chance and replace the module. It controls secondary coil circuit and is, in turn, controlled by the PCM.