Very idle when cold and smokes black when I accelerate hard

[StevoA6]

I've had my '07 A4 B7 2.0tdi 170bhp Sline Avant since November and with this cold weather it can be very idle when I start it and need to warm engine up to drive it. Also when I accelerate just under the hard side its smokes but when I floor it and when the turbo kicks in through the gears it pours out black smoke. MPG is also really low on average calculation - running around 30 but apart from that it runs really well.

Any thoughts?

Cheers

 

[SDHA4SLine]

Boost leak