The problem is likely to be the butterfly valve inside the throttle body which gets sticky because of a build up of oil. The cold oil deposits will be holding the valve closed while the ECM is trying to open it to prevent a stall. It also introduces a lag (hence hunting happens sometimes too).
Get a can of carb cleaner from Halfords. Remove the air conduit from the throttle body (slacken off the large jubilee clip). With the engine running, spray the carb cleaner in. Put another way: get her air filter off and spray the carb cleaner onto the primary butterfly wing (seen when you take off the air filter).
Hopefully that quick fix should cure it for you.
To clean the throttle body thoroughly it needs to be taken off the car but, do that, and once back on the car it would need readapting with diagnostic equipment (Vag Com or similar).
Chicks Fan
December 2008