Interestingly, on the E90 series with the N52 engines, the MAF sensor is not a primary sensor.
On older models, the MAF was critical to measuring input airflow, and the output from the maf fed directly into the fuel calculation.
It seems now that on the E90 N52 cars, that the MAF is just a secondary sensor, and the output from it is only used for minor trim changes from the basic fuel map.
So when you unplug it, the ECU just goes to using default values which were hardcoded from new, and although theses values are not optimal for economy, they sure seem to be for power, since the car went like new when the MAF was disconnected.
However, drive it without a MAF for more than a minute and the DME will throw a yellow CEL on the dash since it's not heard from the MAF for a while.
I've ordered a cheap cable from Ebay to see if I can't access the history of fault codes...