Hi all, 84 vanagon, inline Jetta 1.8liter running on Digifant system,
same as the older Vanagons.

  Ok so here's the symptoms and the pertinent back story, if someone could
send me after the right fix I would certainly appreciate it..

  I recently replaced my 02 sensor and fixed a loose vacuum line and the
engine has been running great...until just now.   It began running very
rough, but running smooth again for a few seconds after turning off the
ignition and back on...So I 'nursed' it home and put it up, crawled under
to check the O2 sensor...the last thing I fixed...Sure enough, that O2
sensor plug (flat, four prong) was partly loose...re-plugged it and
......after a few seconds, it again began to run really rough again and it
smells really rich.  Turn it off and on....smooth for a few seconds and
back to rough....    So, I unplug the O2 sensor plug, re start and it stays
smooth....
    So me thinks I have a problem involving the O2 sensor (it was a new
one, I installed it about 400 miles ago only) or one of the wires or
something that gets a signal from the O2 sensor...What the heck should I
began with here?...I did use some contact cleaner and make certain the plug
connection is good.
   I am about to go out and open up my wires between the plug and the
sensor to check and make sure those splices are good...Is there anything
else that may be causing this?  Oh, I also checked that the ground wire for
the O2 sensor has a good connection.   Yes it seems to.

    Help.   I don't want to run with a disconnected 02 sensor because I
have been getting such great gas mileage since I put the new one in....2+
mpg better than before I replaced it.    Oh yes....messing with the
throttle switches and the connections on the Temp II sender, that makes no
change in how it runs...

  Don Hanson