nepbug

STi 6MT has a slightly different transmission mount. Also, the STi shifter is a little different so you will need a 6MT knob as well. I think the STi shift linkages still work fine with the Forester still having the crossmember spacers, but there is a chance that they will cause the shifter to hit your shifter trim.

Dirty MAF might do that. That's an easy one to start with. Is it only when you downshift? If you floor it from a standstill will it buck around when it gets to higher RPM?

Air filter been replaced recently?