First and easiest is to swap out the idle stabilizer.  Find a known good used one on the list or on The Samba.  This is what fixed my son's '87 when it behaved like that.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of John Rodgers
Sent: Wednesday, September 07, 2016 6:32 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 1991Carat w/auotranny: IDLE SPEED?

My Carat with new engine and tranny doesn't idle correctly. When in gear with foot on the brake it idles as it should: 950 rpm. But shift into Park or Neutral the rpm runs away into the 2000's or greater' any ideas on this?
What's causing it?

John