Based on what I saw while there you definitely have an O2 wiring or ground problem.  While driving when it acts up cycle the ignition off- on. If it clears up for short period the diagnosis is confirmed.

Dennis

Sent from my Windows Phone
________________________________
From: Antony P Marsh
Sent: 12/9/2011 1:03 PM
To: vanagon@GERRY.VANAGON.COM
Subject: The Vanille Shake Syndrome

Dear Readers

Sorry to bother you but up against what appears to be the Vanagon syndrome.  After starting from cold the engine runs OK but when it gets warm it coughs and splutters, seems to be missing and barely gets to 2K rpm.

Wondered if you have any ideas or suggestions?  Here is what we have done so far.

Replaced the gear shift linkage nylon balls and other parts and the shifting is like new, smooth, precise and is excellent.  The soup spoon gear lever is no more.  Thank you to Dennis Haynes for his diagnosis and Ken Wilford for his fast sending of the necessary "bits".

Replaced 02 sensor with new Bosch sensor with three lead attached - made no difference.

Replaced the very red rusty fuel tank, all ensuing fuel hoses attached to the tank, new Bosch filter. The fuel pressure is excellent (35 lbs) and the fuel is no longer rust colored - made no difference.

We discovered a pig-tail already installed in the engine which looks like it has been there a while.  I have another that I tried - alas no change.

Discovered a crack in the distributor body - on removal - the crack turned into several separate pieces.  Thinking this was it - replaced it.  Still the same.

All the spark plugs are new Bosch, adjusted correctly.

What I can't get over is how well the van ran on my way northern Florida, power was great, 70 mph was no effort and I was checking milage at 20 mpg running the AC.  Then it started with the cough - still sick......

Kindest regards

Peter Marsh
Naples FL
239 595 6171