The Mass Air Flow (MAF) Sensor measures the flowrate of air through the air intake before reaching the engine. Since the density of air changes with temperature and pressure (due to ambient temperature, altitude), the ECU needs this information to provide the correct fuel mass to the engine.
So WHY is it important to clean the MAF Sensor?
Over time, dust and oil particles will stick to the hot wire (what measures the flowrate of air) and essentially "bake" on and distort the measurement. The result can be rough idling, poor acceleration and engine starting, and overall worse gas mileage. Cleaning the MAF Sensor can remedy or avoid these symptoms. Also, you can avoid the costly replacement of the MAF Sensor by cleaning it regularly. I usually clean mine at every oil change interval - doing it is quick, easy, and cheap.
CRC Mass Air Flow Sensor Cleaner (available at any auto parts store, costs about $7)
Philips head screwdriver
Level of difficulty:
CRC Mass Air Flow Sensor Cleaner:
Open the hood and locate the MAF Sensor, on top of the air duct between the air filter and throttle body, circled in blue here:
Disconnect the wiring harness, remove the two screws and carefully pull the MAF Sensor from the housing. Then, spray the MAF Sensor with the CRC. The hot wire (circled in blue below) is the important part you need to clean, but I usually just douse the entire piece with CRC to remove all particulates. Just be careful NOT to touch the wires - just hold it by the part where the wiring harness was connected as shown below. The cleaner will evaporate in a few seconds; let it completely dry before reinstalling (carefully reinsert the sensor, attach two screws and connect wiring harness). And you're done.