Simon
it has had a lot of people looking at it in the past so I am unsure of what I have taken on!

I know what you mean it's like startrek but in reverse, you are boldly going where every inadequate 5/8 has been before

E39 is a 5 series so I'm unsure what car you have.
Please clarify if it's a 3 series or a 5 series and the engine capacity.
Exhaust gas readings would also be helpful to figure if it's really running rich.

Gerard