Job 07.3-121 Help

[mwoodland]

I'm running out of ideas at this point. I've started several threads on a driveability issue with a '90 300E, and am not getting any input to speak of.
This is a continuation of the Huge Flat Spot / O2 Sensor wiring threads.
I got a chance to check out the O2 Sensor-to-Control Unit wire, and it checks out at 0 Ohms, and is not shorted to the shield, but the shield shows about 4 K Ohms to ground (Pin 32, if I recall correctly).
The O2 Sensor is putting out about 0.9 VDC at idle when warmed up, and 12-15 mV at 2K rpms.
Idle Duty Cycle cold is 50%
Idle Duty Cycle hot is locked in at 8-10%, i.e dead rich.
Duty Cycle is unresponsive to connecting/disconnecting the O2 Sensor.
Air Flow pot was cleaned and adjusted to a minimum Pin 2 reading of 0.9 VDC, it would not go down to 0.6-0.7 VDC.
Could anyone help me out with this test routine for the Air Flow Pot, Job 07.3-121. I don't have access to any printed or virtual information yet.
Also looking for a recommendation for book, or CD compatable with Win 95/98 that could help.
Plugs, wires and cap have already been replaced.
Car is currently running semi OK with EHA disconnected, and dead rich with EHA connected, w/huge midrange flat spot.
Help.
Mark