Suddenly adding a bunch of fuel suggests either a vacuum leak or a failing fuel pump to me.

Could it be a MAF? Sure. But that's not my first choice. I'd be doing a fuel pressure test and looking for vacuum leaks first, though.

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2011 M3
2006 Sierra 2500HD 4WD LBZ/Allison
2004 X5 3.0i 6MT
1995 M3 S50B32
1990 325is
1989 M3 S54B32

Hers:
1989 325iX
1996 911 Turbo