Hi Mate
Some MY99/00 cars go through MAF sensors atleast once a year even without an induction kit, you are lucky mate, how long have you had the K+N fitted and do you clean the MAF regularly? ( just interested thats all )
There are other aspects of fitting an induction kit which can harm the MAF ie poor filtration, the airflow over the MAF and vibration, all I was stating was that when I have asked any owner on a faulty MAF thread what if any induction kit they have been running 99% stated they were running an oil based filter.
Cheers Iain