Did you ever get your DME updated?
SIB 12 15 14 was put out to address the idle surge issues when coming to a stop.
See this threads:
http://www.1addicts.com/forums/showthread.php?t=1033690
http://www.1addicts.com/forums/showthread.php?t=1205265
My 2013 135is DCT was having the same issues, which were exacerbated by the AC being on.
The idle would always drop to about 500 RPM, then surge up over 1k, then settle down at 700RPM.
To add to this i was having bad throttle delay/lag occasionally where the car wouldn't do shit when i was pulling into traffic which is very dangerous.
I got the update about a week ago, my car is out of factory warranty so it was 2 hours of labor which my extended warranty covered thankfully.
The throttle delay appears fixed, there is still a little idle surge but its not nearly as bad as it was previously. HOWEVER, i will say that the loud burbles and pops that came with my PPK and Performance exhaust are gone, the burbles and pops are very muffled after the update. Im hoping my PPK wasnt erased in the process of updating the DME, the SA said it wouldn't but im waiting for another knowledgeable person to chime in. I miss my burbles and pops.