I got the same thing! I have a vt-1 550 kit. Just installed a week ago. During the first 10 cold starts it was idling like a banshee. I believe this is normal. Also I do feel like the car is about to stall almost everytime i come to a stop. It almost hesitates. I have no doubt in the shop that installed since they've installed easily over 50 kits? (give or take). Now I've put another 100+ miles on it and it's working almost better every day.
2010 E90 M3 ESS-vt1 550 SOLD but never forgotten
2015 F80 M3: JB4 and MPE