Oscilloscope Waveform Of The GM MAF Sensor
If you have access to an oscilloscope, this is what the mass air flow (MAF) sensor waveform looks like at idle.
If the MAF sensor is good then at idle and at any RPM, the waveform will stay perfectly formed. Also, as you accelerate the engine, the wave-length will become shorter while the wave amplitude stays the same.
Now, if the MAF sensor is bad, the waveform will have missing pieces or no waveform will be formed at all.
If this info really saved the day, buy me a beer!