I'd try to figure out what's the = matter here, since the car was designed to run *with* the O2 sensor.
 
It sounds like the car is running way = too rich with the O2 sensor hooked up, so the first thing I'd do is just test the = basic functioning of the O2 sensor itself with a voltmeter.  Also, = somewhere in the archives is a long article written by hugie@lindy.stanford.edu entitled "1981 Van running rich, FI problems SOLVED."  The problem, if I remember correctly, was = that the coaxial shielding wire for the O2 sensor was grounding out at the large = black ECU connector.  You might want to try and find that article.
 
Not having a catalytic = converter installed shouldn't affect the functioning of the O2 sensor.  But, why run = without it?

----------------------------------------------------------------= -----------
Tom Young           &n= bsp;          tomyoung1@home.com
Lafayette, = CA 94549        '81 Vanagon
--------------------------------------------------------------= -------------
----- Original Message -----
From: Schmidt
To: vanagon@GERRY.VANAGON.COM =
Sent: Sunday, February 04, 2001 = 9:03 AM
Subject: more o2 trouble

Since the o2 senser is in the news = here lately,  I am wondering if anything would be hurt(other than = ozone) by permanently disconnecting the booger.   My 84 frequently had = the famed symptoms until I dc'd the o2 senser and then they cleared = up.  Bus depot sent me a brand new one which I installed per the instructions, = but the problem resurfaced.   Again, said symptoms are = : 
 frequent loss of power on = the highway, whereupon the van won't get over 60 mph or pass anything even when florred,
very rough idle
very poor response to the accel = pedal,
horrible gas mileage
 
***DOES THE O2 SENSER READ WRONG = AND FOUL THINGS IF THE CAT HAS BEEN REPLACED BY A STRAIGHT PIPE?  THE CAT = IS DISTAL TO IT, BUT PERHAPS A CHANGE IN FLOW IS SCREWING UP THESIGNAL TO = THE "BRAIN."
 
Again, without the senser, the van ran wonderfully = for several days and I'm thinking it's better to run with the exhaust a = little dirty than to get 10 mpg and have NO power.
Can I just disconnect this for good?
Jay in Windiana