No. or at least I doubt it. I just can't find any info on that chassis b/c it was in between on the diagnostics and emmssions mandates, being early cal.

The reason I had you try the relearn is that being an early 16 pin CAL system , it may have had adaptations, but if it did not, then trying the Memory clear procedure would just do nothing b/c there would be nothng in there to address. If there was no memory, you would just be redoing the code clear procedure. I think , as you do, that memory came a couple of yeares later w/HFM and LH 12 pin.
That car has MAS Controller according to my info , so I am unsure on this point.
I would not rule out the 02 sensor as that is where things are pointing. Duty could also be the problem, being out of 02 range. And OVP is feed for duty, so is there a feed problem there ..???
I would look at 02 first...

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A Dalton