What can effect the cold start on the duratec se?

The car has an intermittent problem where occasionaly on cold mornings the car struggles to start (as if the choke isn't coming on). It fires but you have to try and keep revving it otherwise it will stall, but once the engine has warmed up a little it's fine.

The car runs great otherwise.

Is there an icv on this engine? or is it part of the electronic throttle body?

Any suggestions?