Auto GearBox slow pulling off

[26sj]

I have an 04 facelift 3.0d sport auto.
after diving, for aurguements sake , say you come to a roundabout, you wait for a gap, then when you hit the acclerator pedal there is a half second delay before it move.. its may seem like nothing but when you are sitting there for that short time watching you gap get smaller, then all of a sudden the car bursts into life.
The dealer has checked the car, fitted new turbo and airflow meters, but still the problem persists..

any one else have this problem?
Has anyone got a cure?

thanks