Hi.
Don't know about any fancy words like 'algorithm' ..........plane English is
fine.
Sounds like the Idle Valve on top of the engine, or more likely, the control
unit for it, which is hidden behind the right tail light.
You could look in the Bentley manual for algorithms about testing. 
Scott
www.turbovans.com 

it would be fun if you wrote an algorithm for trouble shooting a simple
110VAC house incandescent bulb being out. 

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Jeff Clayman
Sent: Monday, October 15, 2007 6:12 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 1987 VAN IDLE

I have an 87 2.1 with a/t and my engine seems to get stuck in fast idle
after driving on the highway at 3000 rpm for 30 mins or so.  In drive at a
stop it idles at 1500 or so then kicks up to 2000 rpm in neutral?  Anybody
know the trouble shooting algorhythm?

Jeff