I have a 2000 corolla. It is displaying P0171 code. Measured the mass flow sensor voltage, At 750 RPM about .1 volts and at 2000 rpm about 1.8 volts. Looked at the O2 sensor down stream and it stays steady at .750 volts unless I punch the rev up the engine, looked at O2 sensor on exhaust manifold and it cycles between .1 volts and .7 volts any ideas.
