I just bought an '89 Vanagon. The engine isn't oringinal so I'm not sure exactly whats in it, though I'm pretty sure it's a Digifant 2.1L. Does that sound right. I've purchased the Bently Factory Repair Manual and have found it to be a great resource. But I am still unsure why the engine runs so poorly. I know that the owner before me ran the vehicle for a rather long time with an unoperable Air Intake Meter. I know that it ran way too rich on gasoline because when I removed the spark plugs and the O2 Sensor they both had an obscenely mesurable amount of carbon buil-up around them. I replaced the plugs and to be sure of proper function I replaced the O2 sensor also. But before doing that I replaced the the muffler with another used one and removed that catalytic converter (I know the Cat was clogged and I think the muffler was also).
Before I replaced the O2 sensor, I ran it without one and the engine ran smoothly, though still extrememly rich, about 12mpg. Now I've put a knew one and and wired it in, but give the engine 2 minutes and I find that at low RPM's the engine seems to be getting too much fuel (or perhaps not enough air?); it boggs out and nearly dies. If I turn off the engine and restart it, the problem goes away for a few minutes, I would assume because it takes the computer about this long to register the info it receives. 

I'm just not sure what the next step would be to solve my problem. This is my first Volkwagen. I am a capable mechanic do as much of my own work as possible. If anyone can point me in the right direction it would be greatly appreciated. Thanks, I loook forward to the continued use of this e-mail server and the people using it.