Thanks Arthur, all vac lines relating to the AIR and EGR sys from Intake Manifold base to Engine front to respective components checked out well.

I was confused with the combonation of AIR and MAF in the description of fault 4 on the ODB check, not sure why they mention both components with one code.

Anyway, I'm going to inspect, clean and lube the throttle linkage tonight and see where things stand.

Thanks