Basic settings are not right. 
Ignition timing, open loop fuel mixture, throttle gap when closed. 
Make sure vacuum "retard" on distributor is working and throttle closes far enough to get manifold vacuum to fully retard the timing with throttle closed. Test with timing light.

Dennis
  

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Mike Riley
Sent: Tuesday, August 17, 2010 7:01 PM
To: vanagon@GERRY.VANAGON.COM
Subject: idle problems

strange problem with 1985 manual 80,000 miles.
surging idle,
 throttle body tight and returns to stop every time. switch ok and working.
all idle booster and cold start valves have the vacuum blocked at the manifold<makes no
difference>.
vacuum advance seems tight and no leaks.
car will surge at random to cutoff and continue to do so untill the throttle is blipped a random number of times, then it is ok for a while. any ideas?  runs great otherwise.
thanks
mike