PASSAT SPORT 2.0 2003. problem with initial throttle response, hesitation when changing up or returning to throttle from cruising. With hood up there is a distinct sucking type noise prior to pick up, like a valve sticking. Been into dealer who denies a problem.

Any similar experiences or advice please?

Is the check engine light coming on? You might want to check for something caught in the air intake system (filter, air box, throttle plate, etc...), also check for air leaks at those hoses & rubber boots. You can also check the vacuum hoses around the throttle body