Not the plug, not the rotor not the O2 (Safe mode) not anything related to
normal maintenance.... This is so incredible that mechanics try to change
those parts, a simple check of the plugs, rotor, cap wires is enough to tell
everything about those, it's quite evident that you have a FI / elc related
problem.

Check the basic (fuel, air, fire) I would suspect a few things:

-Have a fuel pressure test done to eliminate the fuel pump and regulator
(sound to me like the regulator could be a problem, but you should see black
smoke in the back).

-Find a fellow Vanagon owner and swap the AFM (am sure you have the
harness???Vanagon syndrom)

-Carefully have checked the electronic advance system and (pic-up) in the
distributor, check this one for any slack, gap, broken parts.

-Swap ECU

-Carefully clean all possible grounds; check all connector plugs including
the injectors one.

This is it, you have one of those element defective!!!

Hope that help
http://www.benplace.com/vw2.htm