Timing / Mixture / CO overvew?

[whiffin]

I have a 1990 (G) mkII 8v GTi

History: For a while I think it's been too far advanced as it's been "pinking". Also I know the mixture and CO levels are wrong (it's too rich). I also have a little crankcase compression. It recently failed the MOT on emissions (CO 7 rather than 3.5). At high revs under load the engine sounds tired ... but I think this is quite likely due to the above problems rather than a screwed engine.

What I want is to be able to put this right, but with so many factors I dunno where to start (there are even two screws (micture/CO) just for mixture).

If I take to a garage they'll probably try and sell me new injectors and the like rather than honestly just tune it.

I live in Salisbury, Wiltshire (nr Southampton)

Any ideas? All help appreciated.  

A

[golfvr6]

one screw on the throttle body is the idle speed  setting, the screw by the air box/ airflow meter is the co adjuster screw.
use a gunston colortune sparkplug or a co tester to get the mixture right, and get a strobe timing gun to do the ignition timing, or you could set up the static timing marks.