Chad, all- I'd like to know the solution to this as I have the same problem.
I recall my 84 having full power and smooth idle while my (1yr) old o2
sensor was disconnected and I awaited the new one from BD.  Symptoms
returned with the new properly installed o2 sensor.  I'm sure my mpg would
improve if I dc'd the sensor forever. I got dem ole
intermit-no-power-crappy-idle-fill-the-tank-every-140-miles blues, mama.
Things that MAY affect the o2 sensor performance on mine:  I have no cat-
just the straight pipe(cats are expensive).  Maybe it is a bad ECU, but why
is it not bad with the o2 sensor dc'd?
I have the feeling that the most affordable, least time consuming answer is
to cut and tape that one little wire.  I hate to throw in the towel like
that, but nobody seems to have the answer.
Let me know if you correct the problem.  I *KNEW* mine wasn't the only van
with this problem!
Jay
84 wolfsburg westy
new plugs, plugwires, idle stabilizer,  cap, rotor, ignition switch, AFM
cleaned per archives, grounds double-checked, new o2 sensor on 1 y.o. entire
exhaust, no vac leaks, no fuel starvation, no cat to clog yadda yadda yadda
PS: I bet when your symptoms appear,  if you shut off the eng for a few
seconds you will temporarily cure this.  ARGH!

>I originally asked the question about the O2 sensors today and how my
crappy
>idle and hesitation disappeared when I disconnected my O2 sensor.  Well
>today I took it upon myself to replace the O2 sensor and low and
>behold......the new one makes it run WORSE.  The idle stumbles really bad.
>When I coast to a stop with the clutch pressed in the van almost stalls (ie
>all the leds come on on the dash) but keep running really rough. I noticed
>while coasting to a stop the tach drops really fast all the way down to
>~400RPM and settles around 750-800RPM with the sensor connected.  When
>coasting to a stop with the O2 sensor disconnected the tach drops slower
and
>settles smoothly at 1000RPM. Any suggestions what I should do now????????
>Will my fuel mileage go to hell if I drive with no sensor?????
>thanks,
>Chad 85GL
>