Greetings and thanks to all those whom have helped me in the past.  My respect goes to you all.
Now my problem...fuel mixture.  I've been fighting this for over a year and I'm getting frustrated.  Let me explain:
Since I've bought the van, it always run a little rich.  Thinking my problem was caused by the cracked rear exhaust manifold, I had it replaced...along with the muffler and the o2 sensor.  The PO (or PO's mechanic) had messed around the the AFM (spring tension) and can't get it back to spec for anything.  When I test the voltage at the o2 sensor I'm getting about 0.9v...if I try to lean it out, it runs like crap (lean misfire).  If I set it where it idles good, it runs too rich and can't connect the o2 sensor to the circuit or it will run even worse and has a total lack of power.  Is it normal for these engines to want to run so rich???  I borrowed a friends AFM last night and it seems to have smoothened out the power band but still has a lean misfire.  What should I check next?  
BTW: Unplugging the fuel pressure regulator (and blocking the vacuum hose) has no effect on the mixture.  Can an increase in fuel pressure cause the engine to "want" to run richer???
Recent tune-up, new air filter, timing and idle are set correctly.  Temp sensor II seems to be in spec.  The Bentley manual hasn't been too much help without access to a "sniffer".  Fuel economy has been somewhat poor up to this point (about 15 MPG).  Any help would be much appreciated at this point.
TIA
Karl Batzler
84 Vanagon 194,000 miles  4-speed
87 Audi 5000 S
La Quinta, CA

[text/html]