BMW: BMW rough idling during cold start for 30 sec, 2005 bmw 325xi, bmw 325xi

Question
Hi,
I know you are proficient in the earlier models but I thought my question could be a general one.

I have a 2005 BMW 325xi (E46) and it has about 10k miles. Three days ago I filled up the tank in the evening and since the next morning the car idles roughly and sometimes even stalls, during first 30 seconds after starting the engine. I should note it only does it when the car is cold. After 30 seconds, the car increases the RPMS to above 1,000, then the drops, and the idling becomes smooth. Then it sometimes stalls while it is still cold and smoke comes out of the exhaust. Once the car is driven for a while it all goes away and the exhaust becomes clean again. The next morning it starts all over.

The car hasn't had an oil change since its first day since BMW recommends 15k intervals. Do you think it maybe oil getting into the fuel or could it be just bad gasoline?

Answer
Nathan, I wish I could help you more, but these later models have EXTREMELY complex electronics, and it would be very hard for me to diagnose the problem with out me seeing the car in person.  It could be a wide range of issues, but something to note, these cars will idle up during cold starts.  They should idle a little higher (i.e. 1100rpm instead of 750rpm) to get the engine up to temp quicker.  
 Unless you had water in the gas, it should not be the reason, I think it's coincidence.

 The best thing would be to take the car to the dealership and have them plug their scan tool into it to get a proper diagnosis.  Unfortunately it's expensive, but sounds like it's your only alternative.  Hope you have a warrantee!
 I apologize for lack of knowledge, but this is all I can contribute.
 If you have any problems I can contact some BMW mechanics and ask if they know of this issue.

 Take care,
 Josh