I have a miss at high rpm sometimes in my 1991 mustang. With the engine running I pull these two codes 41 and 91. "o2 Sensor voltage low sensor lean" my fuel consumption seems to be high and the car just isn't running right. I have replaced the o2 sensors that didnt help. Does anyone out there have any idea what this could be. I tuned the car up (plugs, cap, wires, rotor, I have tested the coil and the ignition module both check out. Could the stock fuel pressure regulator be bad? I have also replaced the fuel pump with a 190lph FRPP model and I replaced the filter at the same time. Any help here is appreciated. Thanks