I had a problem with an 87 Vanagon that was an intermittent failure to run
situation.  Sometimes it wouldn't start and sometimes it would just die. I
traced the problem to a loose solder joint in the ECU.  When the joint  heated up
the expansion would cause the connection to fail and the van would  die.
After spending about $10 on a magnifying glass and a small soldering  iron the
problem was fixed.  I took the cover off of the ECU and tapped  ever so gently
with a plastic rod until I found the joint that was lose.   When I tapped on it
the van would die.