RE: 1991 Audi 90 diagnostics

[Mark Zvolanek <mzvolane@sydney.ipex.com.au>]

Phil
Thanks for extensive description on fault codes.

You say the prerequisites are:
  Fuse 24 OK
  Control unit power OK
  Engine warning lamp OK
  Fuel pump relay OK.

Strangely enough I dont have fuse #24, my fuse box only has 21 fuses. It   
is the one near the engine bay, close to (under) the wind screen on   
drivers side isn't it?
I dont seem have the engine warning lamp either.
Few weeks ago I even took out the instrument panel to check it out.
I only have four lamps on the lower half of the instrument cluster, there   
are holes fore some more lamps, but there is what looks like Audi   
authorized sticky tape covering empty holes.
Looking into Bentley engine warning light space is taken by "air bag"   
lamp shade, I could tell when I looked at it against ligt. The wires (as   
indicated in Bentley) for the warning light are not even at the connector   
(the pin has no wire) that connects to the back of the instrument   
cluster. None of the unused holes did have engine symbol shade.
This morning,before I went to work, I started the engine a put a spare   
fuse into the fuel relay, just to see if any of the other lights would   
light up, but nothing lit up.
Now here comes the strange bit, after I removed the fuse from the relay,   
with the engine still running, the revs suddenly went up from 1000RPM   
(engine still cold) to 1300RPM and there the revs started pulsating   
between 1200 and 1300 RPM, up down up down up down in roughly two second   
intervals. I got spooked.
Anyway so I drove off and at each give way sight the revs were doing the   
same things up  down etc.
Untill I went up a hill, where I had to put my foot down and the revs   
stopped pulsating.

Would you have any ideas what is happenning here?
And also what about my engine dignostics, what else should I try?
Are there any other Australians or New Zealanders out there with 1991   
Audi 90 2.3E (NG motor) that were able to read the fault codes.

Mark Zvolanek