Well, spent sunday afternoon and evening on further diagnosing. Here is what I did today:
I put the car on my Werther lift, and swapped the oxygen sensors. No change, it still fails on the left bank only, so that eliminates the O2 sensors.
Then I tried something different, started the car and kept it running at 1500-2000 rpm, with a few revups to 3-4k. I did notice that around 4000 to 4500 it starts bucking as if some kind of rev limiter is activating intermittently, which I do not think it should??? But anyway, as long as I kept the rpm's above 1500, the ASR light NEVER came on, even after 15-20 minutes running!!!
BUT as soon as I let it drop to normal idle, or anything below about 12-1300, the ASR light and limp mode come on within a few seconds....... If I restart the engine, the light is off again, but will come on as soon as I allow the engine to idle. Could it have something to do with the pedal position switch/sensor, or the cable adjustment????

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Harmen
93 600SEC
03 CLK320
05 BMW Z4 3LITER
00 LEXUS GS300
91 ACURA NSX
97 JAG XJ6L
73 CITROEN SM
74 CITROEN SM
73 LAMBO ESPADA
61 AUTO UNION 1000SP
56 190SL