Rough idle on cold start an black smoke

What is your question?

At every cold start the car idles very rough almost stalling. An at the same time it has black smoke coming from exhaust. It does this for about 45 seconds then clears up an runs normal after the fact.

What makes this problem better or worse?

Only on cold starts

How long has your 2009 Pontiac G8 had this problem?

3 weeks