Chiming in to say I'm currently chasing down what seems like the same problem in my 04 sport. Had o2 sensor codes on in the background for months, yesterday on the way home from town the truck suddenly has no power, CEL flashing on and off, bucking under partial throttle, and gas mileage goes way down. No other codes other than p0174 p0175 p0137 and p0138. O2 sensor voltages look weird on the OBD scanner app I have. Head gasket was replaced recently, coils are fairly new, no misfire codes but there was a definite misfire. I ordered 4 new NTK o2 sensors, I'll see if that fixes things.