The MAF is located on the pipe that comes out of your airbox. It's a little black plastic thing held in by a couple of anti tamper torx screws. Remove the cable and undo these, and lift it off very carefully. You will see 2 prongs with a wire running between them, this is the sensor. Give it a good spray with electrical contact cleaner. Connect it all back up, bu leave it for a good hour to evaporate and dry off properly. Start your car and away u go! This is a guide for a 2.0 gti but I'm sure most are similar. I did this to mine and it sorted it out a treat! Hope this helps mate