I would have 50p on it being an Air flow meter problem, ( especially at 6 years old )

Sit in the car let it idle and then give it full throttle, See how quick it responds, if its a bit stuttery or slugish revving up an AFM should cure it. ( this shows up on 1.0 models a lot easier than it does on 1.2 models for some reason ) And you will soon notice the difference after fitting a new AFM if it has cured it.

H.T.H. Tony.

P.S. Don't pay silly money for Dealer ones.