This chap has the later electronic (or HFM) system - it doesn't have EHA, ICV etc. You're thinking of the earlier CIS (or KE) system.

I am a KE person but from the experience I had with my son's Golf Gti, I'd start with the MAF - try cleaning it with contact cleaner and one of those things one uses to clean out a baby's ears. The Gti is running fine 18 months after the MAF clean but the baby's got filthy ears.

Good luck to you.

RayH