Ok, time to put on your thinking caps.  Can anyone solve this by
sheer brain power alone?

Details:
   1985 1.9l Westy w/Auto Trans and Air Conditioning
   145k miles
   Compression fair (around 120-125 each cylinder)
   Recently replaced Digital Idle Stabilizer
   Recently replaced AFM
   Timing @ 5BTDC

Symptoms:

When warm runs fine.  Get 17-18mpg on the highway @ 65mph, so I don't
think there is any gross mechanical problem with the engine or
mis-tuning.

When cold (60F), it starts right up, but quickly (either immediately,
or within a minute or two) the idle is rough and the engine will die
when in Drive, and sometimes even when in Neutral.   I have to keep
one foot lightly on the accelerator to keep it from stalling.  Within
about 10 minutes of driving, the problem goes away.

I've tried setting the idle higher when cold (with a few turns of the
idle adjustment screw).  This solves the stalling problem when cold,
but then when the van is warm, the idle is way too high (1500+ rpm).

I've gone through the Bently and done most of the electrical digijet
diagnostics  (resistances of temp senders when cold and hot, etc.)
without finding anything amiss.

Ideas?