Well, I let the car sit for a couple of days. Started her up and everything was back normal. 49% while warming up, then fluctuation around 50% like in the past, indicating the o2 sensor was alive and kicking.

Today, began experiencing hesitation in the upper RPM ranges. Car still idles fine, and does not hesistate from a standstill.

Checked the reading at pin 3 when i got home- 10%- with a little fluctuation around 10, sometimes sticking exactly on 10 for a few seconds.

What gives? This is very frustrating.

(still waiting on harness)

Mike

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'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E