My '89 White Star has been misbehaving of late.  It started at Buses
by the Buoy: when idling it would occasionally simply stop; but it
would start up again with no problem.

Then a week ago in the rain I began getting an occasional dropout of
a second or two so while drivng.  That night, still raining, I ran
the engine in the dark and did not observe any corona glow or spark discharge.

The following and subsequent days it became clear that rain was not a
factor.  I was also able to see the tach drop sharply with engine
speed (automatic) but not plummet like a stone.  And I have wires
running forward from T-II, AFM, T-I, Throttle switch, O2 sensor, +12
and ground.  The AFM has the factory pigtail and I monitor on the ECU
side.  The only thing I'm not monitoring is the fuel injector drive.
By using a meter with a fast min-max function I was able over time to
verify that none of these was going open.

At this point I was rather confident that it was the ECU, so I
swapped in another one (thank you Harry Hoffman).  It was NOT the ECU.

The following day I fixed the problem, which was gradually getting
worse.  Any diagnosticians out there care to take a stab at what it
was before I reveal the answer?

Yours,
David