It always struck me as odd, that when tweaking the idle emissions on a good ol' Digifant, that you do it with the breather blocked off from the intake. It'd be a rare mk2 these days that doesn't have a little bit of the vapour / oil mist from the bottom end blowing into the breather. Surely a more accurate way is to adjust the fuelling "as tested", ie the same way the MOT man does, sniffer up the tailpipe and the engine in the normal running configuration?
The good old Haynes manual for Golf 2 and 31 Passat 8v, gives 'guidelines' on this, which most experienced mechanics and tuners ignore lol In my years of owning these things and always after maximum response, I set these up by looking at a stable 900-950rpm idle first, ensuring the base idle was right on the throttle body (usually is unless previously mess about with), followed by bypass adjustment for dashpot on a decel to idle, mixture adjustment via the AFM bypass or more critically from the AFM vane, then tweaking the dizzy for best feel after. CO, HC and Lambda can be pre tweaked at the MOT centre and should affect the set up/best feel procedure. 8v dig**** cars, seldom go wrong on the engine once robustly set up like that.
Unfortunately here in Ireland, the NCT test (Irish version of MOT, only stricter) the tester won't make any adjustments during the test.