[scarceller]

The O2 sensor at WOT can NOT cause any issues in the 3.2L Motronic. This is because the O2 signal is ignored in the following conditions:
- any injection pulse width greater than 9.6 milliseconds
- RPMs > 5120
- And most importantly if the WOT switch is closed.
Any of the above 3 conditions does not monitor the O2 sensor.

But you should check these things:
- With accelerator pedal to the floor check that the throttle plate is fully open.
- Also with throttle plate fully open check that the electrical WOT switch on the TB is closed.

It's possible that the WOT switch is not closing and thus you will not run out of the WOT maps in the DME, this results in power loss.

Also have you tested fuel pressure? The lean condition can be caused by low fuel pressure.

No matter you are way lean for WOT, the stock chip usually runs on the rich side at WOT down in the 12s AFR.