Hi guys,
I got this message from a Vanagon owner.  He is having his van running rich, no matter what, he says.  I was thinking of the Temp II sensor, but says "checked out-ok", which I doubt a little.  He has changed computers but thinks that the one he has maybe different to the one he tried.  This car is A/T if that matters.  I thought, any computer to these years would fit.  Maybe not.  
So, what can he do to check more or again?
Anyone?
Zoltan

I'll give you a rundown of what we have tried so far: 
All wiring has been tested and grounds cleaned between ECU and O2 sensor
Temp II sensor checked-ok
O2 sensor checked-ok (new in Oct.)
Fuel filter replaced
Wiring harness attached-no difference
This has never happened to this Vanagon before. It happened after they fixed the ground strap and connections for the Van after a starting problem (intermitent..low power)
They also said they 'fixed' the transmission and now it switches gears at the correct RPMs. 
It runs fine, cold, then goes down the tubes (i.e. loses power, kills, I have to release then floor the accelerator in order to power through the fast decrease in RPMs.) 
I will check anything else you may suggest! I want my own hands in there for awhile. Any computers you can send/lend/sell for diagnostics would be very appreciated.