Oh boy what a bunch of wrong info. First of all closed loop is continuous once initiated except at full throttle. The O2 sensor is evaluated continously once hot.
950 is too high even cold, but what is more important than actual speed is whether the control is in control.
As to why the car won't run at the mixture the O2 sensor takes it, the answer will be costly unless you can properly test the system. I haven't heard one diagnostic word here except situational parts replacing. If you wish to find the answer you will have to test the duty cycle codes and integrator at the diagnostic port left fender. The long term memory should be checked on the diagnostic connector at right hood hinge area. The EHA current absolutely needs to be monitored. Most importantly you will need to know why any of that matters or it won't.
Do you understand closed loop?? Do you understand the O2 sensors part in it?? Can you recognise this activity which is administered by the EHA? I would be glad to explain it again (I've probably done it at least 5 times on this forum), if anyone is willing to follow. It can be done on these early cars with simple tools nothing more complicated than a good multimeter.
Don't mean to be harsh but without understanding, diagnostics are impossible. We are continuously dealing with problems on modern cars that just can't be fixed with just parts.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician