throttle problems

[bigoz5]

I have a problem with my 2002,A3, 1.6 petrol, car engine code AVU.

Basically it has failed the MOT because the tester was unable to maintain 2500 rpm during the emissions test, the car starts and runs fine, on touching the throttle it is controllable up to 1400 but then runs away to 5000+ and immediately drops to idle when released, I have changed the lambda sensors ( he claimed emissions too high) changed the air inlet pipe as it had a split (fault code mixture too lean), cleaned plugs, new air filter but still the problem persists.

It drives fine and is fully controllable up and down........any ideas