If you do not already know, a Mass Air Flow (MAF) sensor ensures that the engine gets the correct amount of air needed to map the air/fuel ratio with the appropriate amount of fuel.
Henceforth, it is a good practice to have the MAF sensor cleaned each time you replace your engine air filter or at periodic intervals dictated by the level of personal comfort.
Personally, I found a periodic cleaning habit to be useful especially if you have an oiled air filter (like those from K&N) installed.
Google online and you would come across many forums with claims that the oil vapour from the K&N filter coats the MAF hotwire over time. Based on my personal experience, I had no problems with my K&N but those claims do make some level of sense. If you think logically, if the oil dries up over time, where else would it go but upstream!
Although the benefits from MAF sensor cleaning will not turn your stock Lancer into an Evo, it's certainly worth the while to know that anything that promotes engine efficiency eventually adds up to either better gas mileage or a smoother engine.
Illustrated in the pictorials are 4 simple steps to getting your MAF sensors cleaned. Do ensure that proper spray cleaners (such as contact cleaners or MAF sensor cleaners) are used in order not to leave any residues.
Just remember, do not touch that hotwire or drop the MAF sensor. Else, you would be doing more harm than good for those little MAFs don't come cheap.