LR Focus no acceleration

[zeuss000]

Howdy Folks, My missus's trusty 03 Focus has developed a rather bad problem, she was coming back from the shops this morning and it started to die on her, she managed to get it back home and i took it for a drive, It idles fine and revs in neutral no problem and when initially accelerating off it seems OK but after driving for half a k or so when trying to accelerate it just dies, still idles fine, doesn't cut out at all but just no acceleration, I could sort of idle home but give it any herbs it just dies back, not cutting out just very weak acceleration, Also I'm pretty sure i can hear some pinking that was never there before.
Thanks for reading guys, any suggestions?
Cheers
Ed

[DZFord]

Dirty / failed MAF sensor?