this has probably been covered on here a number of times... but this is a revelation to me, so am sharing for benifit of those unaware...
A couple of years ago I rebuilt my DG 1915cc water cooled engine, with great help and advice from here and a local VW trained technician (didnt they used to be called 'mechanics'?). Van has run like a dream since.
However....
a few months ago I noticed that she felt flat upon acceleration and particularly uphill, when Id have to change down a gear to compensate. Without load on the engine she was just as good as always, but trying to pick up speed just felt, well, a bit wierd really!. The only thing I could think of that Id replaced were the plugs and HT leads, so I thought they might be suspect. So I changed he plugs back to single electrode ones first and I convinced myself that she felt better (although, not too much!). This week I was going to change the HT leads, although they were changed 18months ago.
Well, Ive just serviced the engine and got 'Monsoir VW tech' to check her over. The timing was tweaked as was the CO (carburetter/fuel/air mixture - for the uninitiated) and minor adjustments were made. We talked about the fact that she had felt 'flat' and lifeless for a while and he went straight for the vacuum advance unit (flying saucer shaped thingy attached to side of distributor). It is cream crackered! The little pipe was pulled off the rear of carb and, by either attaching a test device (modern way) or sucking/blowing down pipe (old way!) it was very clear that the internal diaphram is leaking (when you pop dizzy cap off and look down the inside, then suck on yer pipe, you should see the actuater arm moving the dizzy plate inside - apparently!).
It turns out to be a really common problem, giving the same symptons, and a really easy fix too.
Ive ordered a new one (and new connecting pipe, in case that is also perished) and as long as postal strike doesnt claim it (!) I will be able to update on here sonn... keeping them crossed!
