The throttle switch must be looked at.  It looks like it does not come back
enough to switch it to get to idle mode.  There must be a click when you
release the throttle.
To adjust, you would need to use a small allen wrench.  One does the locking
the other the adjusting.  As you look down on the switch that's under the
throttle valve.
Zoltan

-----Original Message-----
From: Steve Williams
Sent: Wednesday, June 24, 2015 11:27 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Intermittent high idle - able to make "go low"

Hi,

I have a 91 Westfalia, manual.

After driving for a short period of time, when I take my foot off the
gas, the engine only idles down to about 1800 rpm.

If I "burp" the throttle... by pressing gas pedal towards the floor &
releasing quickly, the idle will come down to normal.

These symptoms really make me think something physical, rather than
electrical, vacuum, etc.  However, I've checked the throttle cable &
what it attaches to and everything seems to be travelling smoothly.

Annoyingly, I can't replicate this without driving the vehicle. Humm...
as I'm typing this email, I just thought of driving the vehicle, pulling
over to the side of the road & popping the back open...  but until I get
a chance to do that, is there any "list wisdom" that could give me
pointers on where to look?

Additionally, how tight should the throttle cable be?  There is about
1/2 inch of slack in the throttle cable.  It is not very clear if it's
adjustable on the engine end of the cable or not...

Thanks,
Steve Williams