I know this is a late response to an OLD Thread, but figured I'd post my experience for future Q's.
Experienced same "loaded" power related P2177 code. Car has slightly reduced power at low rpms and poor throttle response. Checked for vacuum leaks, cleaned the MAF with sensor safe intake cleaner, and replaced upstream O2 sensor. p2177 still coming up. I sent the car into a local Mechanic and diagnostics showed that the MAF was failing under load and that my injectors were at 70%. Replaced the MAF sensor and ran a three part injection system cleaning...All Good! No code, the car has all its power back and the A/C is blowing super cold again.. Ya
Man!