Mass Air Flow Sensor is located right after the air box. I am guessing you have the original unit and no CAI
Its the unit that looks like a small black plug with an electrical connector attached to it.
Take off the car by unpluging the connector and the two screws.
Remove it carefully, you should see like a small venturi (plastic tunnel) inside is an electrical heated filament (like a light bulb filament). that is what needs to be cleaned...
Use an electric contact cleaner, and nothing else. You can get it a radio Shack or even Wallyworld.
It does get dirty and give you an engine light error.
Becarefull and dont fuck it up, it cost over $400 to replace.