Peter,

First, disclaimer, I don't know much about VW engines but am learning quick.
I had a very similar problem with my 85.

I received much input about the capacitor fix and maybe tweeking the AFM
springs and tracks.  Go to the archives for this.

I was going to tackle the AFM stuff but when I pulled the unit off I had
some very bad electrical connections.  The 2 booster boxes that receive air
(one is for idle I think and the other is power steering...wish I had my
Bentley with me).  Anyway, the one that connected to the power steering
pump and grounds to the alternator was in very bad shape.  I replaced these
electrical connections, upped the idle a bit which it needed badly and
acceleration has been much better.  Coincidentally, I began using Chevron
techron gas at that time with 1 round of techron additive (about 6 bucks)
and performance has been great...even considered drag racing my subaru wagon.

Anyway, the list had great input and got me through the problem.

Hope it helps.

Scott Longing
Ph.D. Graduate Student
216 Price Hall
Department of Entomology
Virginia Tech
Blacksburg, VA 24061-0319
Ph:  540-231-4039
Fax: 544-231-9131