Did you find a resolution to this?

P1606 (Symptom Byte 38) is for "Engine Torque Not Plausible" - this will tie in with the P0171 fuel system issue and also the symptoms you're getting with the running problems. It doesn't sound ECM related to me, moreso something along the lines of an intake air leak affecting the reading to the MAP sensor, which will throw the fuelling off right across the whole rev range.