Can anyone tell me what this is?

[memmo]

Can anyone identify what this is for me please. Could it be the cause of my car not running very well at low revs on part throttle? Especially in this cold weather?
Thanks in advance:

 

[beachbuggy]

DV valve, looks like a Baileys one.

It could be leaking.

 

[memmo]

Thought it might be, Its a Turbo Dynamics one.
Should there be a standard re-circ valve where it is instead?

 

[quattro1]

does your car idle ok? take your engine cover off, if the DV is connected to a rubber pipe (i think it is going by the pic) check the pipe for splits, mine looked like it had been attacked with a knife!

 

[s3dave]

Is it a recirculating or blow off valve?