You are very close to spec -- you want 0 mA plus or minus 1 mA at idle, and it should run near 0 at steady throttle. 20 mA on startup (key on, engine off). The very negative number is for fuel shutoff on closed throttle. Unless the EHA itself is bad, everything is working, unless the O2 sensor is going and giving bad readings.
Verification would be to drive it with the EHA unplugged -- this will make it run on mechanical only, no electronic corrections. If the rough idle persists, you KNOW it is fuel distributor, injectors, or ignition.
Your idle problems probably aren't fuel related unless you have a dripping injector -- this will make one cylinder run over-rich, and the EHA will then obligingly run the rest slightly lean, and it rumbles. I think this is part of the problem with the TE, but I've not managed to find the time to dig into it yet.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!