another problem which can be overlooked is the fact of the bov being to tight, when u come of throttle and the air blows past the afm cooling it down causing the ecu to throw more fuel in which can cause unstable idle, i heavn't hear of thiss being a problem with subaru, more on nissan gtr's. but this isn't the case wiht you is it? you just have constant bad idle, leaving only what was stated before, a air leak in your system somewhere or a faulty bov.... i hav a turbosmart type 2 on my lib with 15psi runnin through it and have'nt had a single prob. only thing is psshh is getting on my nerves so i may look into a atmo/plumb back....