okay, so... I've had this misfire issue and I have done the following to diagnos it...
1.cleaned MAF sensor
2.replaced the spark plug
3.swapped around the coil packs
3.did a compression test (when cold) and readings were 120,120,110,120
4.tested the ground connections
5.ran a new ground wire to that cylinder
6.took it to a dealer to check it out (it was close to closing on the weekend and they said the injector sounded okay)
7.I've done datalogging and everything seemed normal made a few adjustments
So... with that being said, I called a local shop here (they specialize in subarus) and they told me that it's most likeley a piston ring issue... They told me that they've got a few in with simular issues and they did compression tests on them and have came back normal, plus then they tear down the engine and find burned up piston rings... They said it would be $1800 to rebuild it... So... I'm at a loss at the moment and I just can't see if it were a ring issue that wouldn't show up on a compression test... Please help, I'm about ready to put my head through a wall...