I just posted a book about those codes and troubles i had in the 74mm MAF and MB airbox thread. Others have had the same problems as well after going to the 74mm. My advice is to buy some MAF cleaner, TB cleaner, take everything back off, clean the TB till its nice and shiney, spray the MAF down (original Bosch one) put it in the 74mm housing and then put it all back together. Follow the instructions in the 74mm install PDF. There is also a white hose that comes from the firewall that goes into a black one, it is easy to losen that connection when working down there.

Third time doing it was the charm for me, torque it right and everything will fit like a glove when it's done right. You won't have to force any of the clips etc. If you have an ultra guage or other odbII reader it helps to see the MAF and TB% readings as well.

When I finally got it right it idled high 1-2K RPM and then settled down. It never idled high the previous times. TB position is 0 or less than 1% now where the 68mm was 1.5 - 2%.

I swore every time everything looked and felt tight but it must not have been, regardless no harm in trying it all again and after a couple times it only takes a few mins . Software is def not going to fix a physical problem, if it was there before the tune it's gonna be there after.