I have never come accross this before on a duratec or zetec for that matter, my mate just bought a really nice st170 and noticed it on the drive home, its drives and pulls well through the gears but when changing up under load he gets pinking until it reaches 2500 revs, I could only suggest using higher octaine fuel, plugs, leads and coil pack, he has in the last week changed the lot and his one still does it, any ideas on where I can tell him to go next as I was thinking the AFM