I have a 98' Ranger that has been showing a malfunctioning Mass Air Flow Sensor, I replaced this with a rebuilt unit and had same results. then started checking other items, I read that the ECM is supposed to send 5 volts to the MAF sensor, this voltage is not present ( I am sure I am checking the correct terminal). I replaced the ECM with a rebuilt unit and had the same readings. Thought it could possibly be the ECM relay or diode but the ECM is supplying 5 volts at the TPS. After all of this, had the local AutoZone put code reader on it. It now shows a fault with the Idle Air Sensor and a O2 sensor. I don't know if it is possible that these other sensors could set off a Limp Home Mode and take the MAF offline. If anyone has encountered this, please respond.