A big thanks to Ken Lewis for his advice and encouragement in helping
me diagnose my O2 sensor issues.

The symptoms:  Running rich, very rich.  Gas mileage was 10-11 mpg.
Once warmed up the engine bogged terribly coming off idle.  O2 sensor
readings on the Digitool were whacky -- way high to way low but mostly
high.

The problem:  Seemed obvious that the O2 sensor was shot until I put
another one in.  The symptoms got worse.  Figured it was the infamous
1.9L green wire issue (shielding shorts out to the conductor).

The fix:  While looking at what I needed to do to replace the green
wire I started poking around with the multi-meter I discovered there
was no continuity in the splice and white ground wire inside the ECU
connector.  When I peeled the covering off the splice collar and opened
it up I found a bunch of corrosion.  Cleaned this up with a brush and
flux, snipped off a bit of white wire and soldered the white wire to
the shielding.

The results:  After tweaking the AFM spring according to Ken's
instructions the O2 sensor reading is bouncing up and down between .3
and .6 at warm idle, the engine pulls consistently off idle and the gas
mileage increased by 50% (from 10 to 15 mpg around town).  When the
emissions guys did their tests this morning it passed by a wide margin.
  Last year the HC ppm was at the limit, this year it is reading 15
(25mph) and 17 (15mph) against standards of 189 and 194.  CO% was 0.22
and 0.27 against standards of 2.36 and 1.74.  I checked and the tester
did have the sniffer in the exhaust on my van.

Chuck
'85 Wolfsburg Westy - 'Roland the Road Buffalo'