I am reposting this question because NOBODY has been able to fix it!

I have been completely clueless for almost a year by now about my 89 Vanagon.
I have never had a problem with this it and rebuilt the engine about 3k ago.
It ran beautifully until one day it just stopped running right.

It idles and accelerates fine when cold. Just as it gets warm it starts
coughing and backfiring through the air intake when you press on the gas like
if you would accelerate from a red light. It sounds like it is not getting the
right mixture. It smells weird. It just won't smoothly accelerate and rev up.
You obviously cannot drive the van this way. It will hesitate like crazy,
sometimes it will backfire through the air intake other times it will rev up
a little.

The computer will reset itself and it will run fine for about 30 seconds when
quickly turning off the ignition and back on again. IT IS NOT A mechanical
issue because compression and all are fine.

All electrical test as per official service manual check out fine, computer
checks out fine, new o2 sensor, fuel pressure fine, injectors brand new, coil
brand new, distributor brand new, temp sensors new, grounds to chasis fine,
all resistance tests are fine, relays like fuel, etc. test fine, new plugs,
wires all new, new gasoline as well... It must be electrical but where???

Of course when grounding the o2 sensor the motor will run because it enriches
the mixture... but when hooked up correctly it will not. continuity between o2
sensor and brain is fine, too. resistance of o2 sensor is fine, too. temp
sensor at intake is fine as well,

Does anyone have an idea what this problem is???  NOBODY seems to know what
the problem is... I wonder if we have a real expert here!!!