Thank-you all for you help so far. Until I read Stephen's post, I would
have assumed the MAF sensor for the reasons below - now I feel I
should, test or replace the ground splice.

MAF Tests
I performed the MAF tests in Haynes 4-24 (Air Flow Sensor 1994 and
earlier) Output voltage of the sensor when disconnected between pins 3,
6 should be 2.7-3.2 V (was .15-.03V). Voltage between pins 5,6 should
decrease when air intake is obstructed - it was 0V. The codes shown
after this test with MAF disconnected are
2,5 - Baro pressure sensor
1,2 - Airflow sensor
1,5 - Motor position sensor

Is this a good enough indication that the MAF has failed?

ECU
Resetting the ECU and disconnecting the coolant temperature sensor for
a general test of the diagnostic fcn of the ECU produces
1,5 - Motor position sensor

I guess the ECU is not meant to be interpreted by mugles :>

Ground
Is there any good test of the bad ground theory - such as connecting
the test ground on the ECU to the negative battery or the block with a
good thick conductor and seeing if the problem disappears or looking
for a voltage W.R.T. ground on the ECU test ground?

Thanks again for all the help - I'm proceeding with MAF replacement.