Thanks for the advice, I'll give cleaning those parts a go, and see if it makes any difference to the car. I have some cleaner as I had a Seat Leon which ran like a bag of turd and I tried cleaning the MAF on that.
I've just run diesel engine cleaner through it, still seems to have the massive off-boost spot in 1st/2nd, although I've noticed that I've gained about 1.5mpg on the average run since I used the cleaner so there is some benefit.
Ned I'll be bringing it in anyway as I'm sure my suspension is creaking at the seams and its coming up due a service and cambelt change in the next couple of months anyway. If I've not cured it by cleaning the sensors by then, I'll get you to have a look at that issue.