Vanagon 88 GL Wolfsburg (2.1 L / Kat)

Hello erverybody, I had been following the discussion in the last weeks in
regards to coldstarts, Oxygensensors etc. but cannot access the archives for
an immediate answer so I have to ask you again :

Engine starts (cold) fine but idle immediateley drops and engine stalls, I
have to keep the accelerator down for a little while until engine warm, then
idle perfect and stable at
850 - 900 rpm. Fuelpressure at 2.5=ok, spark ok, compression etc ok (about
8K on rebuild...)

What is the culprit ?

Also sorry for the very boring question is Bosch W 7 CCO the right and only
plug, also which is the code for the 3-prong if that should be the route to
go for me...

Thanks everybody, so far a fantastic winter here in NY both for Vanagon
driving and else

Greetings

Onkel Max