Fuel filter sounds about right.
  Take it out, pour the contents 'backwards' out into a jar thru a paper
towel or coffee filter to see what its caught.  It may be full of a fine
sediment or rust particles.
  I've had to stop on long trip several times to empty my fuel filter, just
to keep on going to my destination.  It kept clogging up, and I kept
emptying it out, until it stopped clogging and ran fine for good.  Then,
when I got home safely, I replaced the filter. It saved me many new filters,
until the problem cleared up.

YMMV,

Mike B.

----- Original Message -----
From: "John Bange" <jbange@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, September 10, 2008 9:28 PM
Subject: Weak..... so weak

> Yesterday my work vanagon developed a bad case of the groggies.
> Started out as an intermittent loss of power, but has developed
> steadily towards permanence. Now O reckon I could do 0-20mph in 3
> minutes with the pedal to the floor. It also likes to stall. Haven't
> had a chance to poke around much. Sounds an awful lot like fuel
> filter. My wallet likes the sound of that. Or maybe air flow meter. My
> wallet likes that too, as I already have a spare. Any other probables
> on the "loss of power" checklist I might've missed?
>
> --
> John Bange
> '90 Vanagon - "Lastwagen"
> '90 Vanagon GL - "Wiesel"