fuel filter

I bought my first BMW, a 2001 M5 in January 2012 with ~56.5k miles. It currently has ~62k miles and is my daily driver. I really thought I would put less than 8,000 miles a year on it, like my previous daily driver (1998 Honda Accord 2.3L 4cyl. automatic), but this has become the family car...

I've been having a intermittant SES that seems to be staying lit more consistently. I'm also having a "Engine Failsafe Prog" message intermittantly. The engine seems to be cutting out at very low RPM's or just off idle, sometimes it almost seems as if it sputters on application of the throttle...

OK, the beast has been backfiring, bogging down in the cold and popping and pinging when I blip the throttle when it is warm. On freeway onramps (especially those hard right ones) the car literally stumbles and two times has gone into limp home mode. The MAFs were replaced as that was the code...