2001 X5 4.4 Stalling.... Additive and Mixture error codes PLEASE HELP!!!

[acidburn]

Hi guys, I have a 2001 4.4 and I'm having massive problems with it. The "SES" light is on and the computer produces 4 codes:

1)Additive mixture adaptation, bank 1 control limit reach
2)Additive mixture adaptation, bank 2 control limit reach
3)Multiplication mixture adaptation, bank 1 control limit reach
4)Multiplication mixture adaptation, bank 2 control limit reach

The car stalls when I just start it and sometimes it takes a couple of tries to get it started and idiling. Sometimes it idles pretty rough and then it goes away. Also the car stalls when im driving, usually when I break and come to a complete stop.

At first i thought the problem was with the Air Mass Flow sensor, so i bought one on ebay and changed it. The "SES" came off, but after about 5 miles worth of driving, it came back on and the problem was worse than ever. It's possible that the Air Mass Flow sensor is bad, but I'm not sure. Please give me some advice and share your knowledge, becuase I can really use the help.

Thanks a lot in advance.