My '85 also runs a little on the cool side.  On the way home from the
Shenandoah National Park Monday, I hit some traffic coming into Washington,
DC.  The slow traffic caused my temp gauge to move up slightly--to what I
call normal--needle just below the light.  For the rest of the trip, it
seemed to have noticeably more power, especially pulling up through 3rd
gear.  On the way down on Saturday, I noticed the opposite.  As the outside
temperatures dropped, the gauge went lower, to the edge of the white mark.
I had less power just as I needed it going up  Swift Run Gap to the Skyline
Drive.  I think I may have a stuck (open) thermostat,  a lower temp.
version, or one that is leaking through?   I have checked the Temp II
sensor--it is right on.  The FI seems rich on cold starts.  Will fooling
with the AFC (it is new) adjust overall mixture or is this a can of worms?
Spotted two other Westy's at Loft Mountain--a nice burgundy '89 and a white
'82 beater.   As always, friendly VW owners.

                                                        Jay