Bosch makes the MAF for Porsche. Having said that, there are various MAF part numbers so make sure you used the .148 or .055 part numbers for an '01S.
Get the codes read, post them in the format Pnnnn here or use the forum's search function to see posts of prior owners who had the same code and see how they resolved. One nice thing about a car so old, someone else has discovered 99.99% of the problems already.
Don't throw more money at the problem until you know more.
Once you disconnect the battery, the air/fuel mixture is, for a few drive cycles, determined by preset default values and is not calculated from values sent by the MAF and O2 sensors.
Could the replacement part have been bad? Sure. Not likely.
Be sure to not touch any of the non plastic parts on the MAF.
More here.