i have been wondering if i've got a boost leak cause i had my MAP sensor replaced when it went out, but at the same time had the recall done on the chargepiping or whatever they did and shortly after that i've started having problems. but i am holding a steady 22 pounds of boost. but at higher rpms my air flow has really gone down. i took the tune off for now went to a mostly stock tune, just a little modified till i figure out what's going on. the plugs look great BTW, golden brown.

 

Any metered air past the MAF leaking out will skew the fuel trims. I'd bet you have a boost leak. It would still hold pressure unless it was severe. Since the charge piping was disturbed/replaced, I'd sure start there. Prob not seated on the intercooler properly.

Could also be leaking around the MAP sensor. There is a leak someplace. Maybe they left the seal off.