So today I went out with scope and DVM in hand to get some measurements.
As usual, upon cold start the car seemed to be running OK.
I started with measuring the AMM.
pin 5 (orange)= 13.5
pin 4 = 0
pin 3 = 2.4
pin 2 (yel/gr)= 0
pin1 = 0
Nothing unusual there. The car began to run worse, but the voltages remained as above.

Car is now alternating between running OK and awful.
Next O2 sensor.
With O2 sensor connected to the ECU, reads a oscillating voltage around 0.5 volts. But, when the car runs awful, the voltage jumps around from 0.3 up to peaks of 8V.! Is this the O2 sensor going crazy, or is it responding to what is coming out of the engine?.
I disconnect the O2 from the ECU. The input to the ECU is at the default voltage of 0.54v. The O2 sensor continues to gyrate wildly, huge peaks up to 8v, and when the engine decides to run smooth, oscilating from 0.3 to 0.7v.

From this I conclude that the O2 sensor is responding to what is coming out the exhaust, and not causing the problem.
High positive voltages from a O2 sensor represent rich mixture, although voltages up to 8v seem way out of what an O2 sensor is capable of.

Last test was the coolant sensor, measured at the ECU, 320ohms with the engine hot, seems about right.

So may have confirmed what I intuited from the plugs and performance, running rich is the problem....but why, what is telling the ECU to run so rich?

Tomorrow's test, injector opening pulse times.

Any other ideas where to look?
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93 245 Classic, M47, IPD, 91 245SE AW70, 89 745, M46, IPD, Dependents-00 S/V 40s