Between the air filter housing and the air inlet duct (accordian tube). Remove the "buckles" holding the top of the air filter housing. Unscrew the hose clamp closest to the circular metal object (MAF housing). Then spray non contact electrical cleaner on the MAF sensor.
Edit. If you look at this picture, the silver looking round tube with the black square on top is the MAF housing (between the accordian tube and air filter housing).
