There is a thread here somewhere posted by a member in Europe. It refers to the the transmission shift position sensor.
Basically it said to put the car in 2, and floor the throttle. At abt 4500rpm the ASR light comes on and the car goes into limp home.
Replacing the part as Mark did seems to cure this problem.

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John
92 500e, 85k, silver/gray,all stock.
96 Club Wagon,Hypertech chipped( College Hauler)
97 320 SL 50k
1980 BMW e21 323 Baur conv.
1990 300GE 99k