Rough idle with misses and vibrations

[Chattergoon Kanhai <kanhai@eng.uwi.tt>]

I am calling from Trinidad..........Greetings!
For some time now(a year) my 1991 Audi80 2.0E, four cylinder car is
rough idlying with a frequent miss. I cleaned the injectors but the
problem did not cease. I finally resorted to adjusting the small air
allen key screw. This did not assist greatly but the CAT keeps on
blinking, because the car began burning too rich.I exchanged the plug
wires - using an extra one- but no improvement.I even shifted the
distributor and this did not cease. Would you guys have any suggestions?
By the way where is the diagnostic jack in this car?

This car was bought as a foreign used from Japan and the manual is in
Japanese. I could do with some info on workshop manuals on this car.
 Regards: Kanhai