Thanks Rubjohnny,
It looks like you have a slightly different setup to me though

I have no EGR or carbon canister system. My engine is a '90 UK model.
I do however have a vacuum inlet on my ECU which is controlling vaccuum advance.
I guess this needs to know vaccuum in the vicinity of the throttle body?
Dashboard conects to the MFA right?
I also have a vacuum conection at the overrun cuttoff valve and some kind of pressure diaphragm next to it. I cant tell if this is the same as the on/off valve and frequency valve on your diagram.
Thanks again,
Manchester