vw passat cold start?

Hello

I have a 51 plate VW Passat 2 litre petrol, recently it has started to have problems starting from cold, it will turn over about 5 times then start but run very rough at about 400 rpm then stall then when i try to start it again it is a bit better after giving it some throttle. also doesent start first time from hot either.
do you have any ideas what the problemb could be ?

Cheers Lewis