Could be carbon buildup-when the car's cold, any carbon in a cylinder, as I understand it, acts like a sponge and absorbs some of the fuel. This changes the mixture to lean, and therefore causes the car to stumble.

I had this problem with my M119 V-8, and a couple of cans of BG 44K took care of it. Good luck!

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo