Brought up the fault codes on My '97 v3 WRX STi and got 23 - Maf sensor fault. It's been doing this weird thing where occasionally i'll start it up and it will idle at around 1100rpm until i turn it off leave it and come back and drive it later... Also makes a winding down ticking noise for a few seconds when i turn it off...?? Car has a well used k&N pod filter, just wondering if anybody has had this problem, how to fix it etc, how much ill be looking at if i do need a new sensor, and if anybody has a factory air filter box, i'm presuming pod filters kill the maf faster than an original box would? Cheers, any help at all is much appreciated!!