Fuel to air ratio on 1994 Mazda B2300

Which sensor regulates the fuel/air mix and how much does it cost?

Asked by for the 1994 Mazda B2300
The mass air flow meter or a MAP sensor (Manifold Absolute Pressure sensor )measures air flowing into the engine and the computer makes calculations for fuel based on this reading. The Air/fuel ratio sensor or Oxygen sensor measures oxygen in the exhaust to determine combustion efficiency and tailors the air fuel ratio depending on this value. The airflow meter is about $350 from the dealer, the upstream O2 sensor is under $100.