If this was an ignition problem, I would expect the van to be hard to
start.  The reported behavior seems to point to a sensor problem that
affects the mixture as it warms up.  The only sensor which uses a high
impedance circuit which could be affected easily by water is the O2
sensor signal wire.  Check that it has no cracks or bare spots in the
insulation that would allow it to be grounded by moisture.  Maybe when
the van is dry and warm and running well you could try using a spray
bottle with tap water to spritz the wire all the way from the O2 sensor
to the harness connection in the engine compartment.

good luck,
Larry A.

Dave Engstrom wrote:
> My 87 Westie has developed a problem.  After the engine is warmed up and if
> it is wet out (raining) the engine will cut out.  Turning the ignition off and
> restarting solves the problem for a few miles and then it cuts out again. This
> is not a problem in dry weather only in wet weather. Any suggestions? Coil?
> Plug wire?  Dist. Cap?
>
> Any suggestions appreciated.
>
> Dave Engstrom
> 87 Westie
> 99 New Beetle
> 68 Bug
> 90 Carat (for parts but runs)
>