"Is there possibly a ground issue? I've cleaned a lot of grounds in an
effort to resolve poor running. However I've not done anything behind
the dash."

Hey Mark,
Yes, there are a lot of important grounds behind the dash.� Many of them are attached to the chassis behind the fuse panel.� If you drop the fuse panel and shine a flash light on the drivers side chassis you will see two "crown" style connectors.� These connectors are round and each one can hold many wires.� Quite a few�ground wirres attach to these two connectors.� These connections corrode with age and can cause issues.� Worse yet, a leaking windshield seal will inevitably route water directly onto these connectors wreaking all sorts of havoc.� I suggest cleaning the heck out of these grounds.� Many Vanagon owners find that this clears up all sorts of weird electrical issues.� Be warned, it is a�PITA to get to them, but can be done.

good luck,
jake