I am trying to get a thread for people who have had these, and what was wrong or what they did to fix them. I am also trying to see just how many people have had this problem already, it seems like there are a few of us along with others who own WRX's.
I have a cylinder 4 misfire right now, and it seems to be my injector. I swapped coil packs and spark plugs between the 2 and 4 cylinders, but then still had the PO304 code for a cylinder misfire. Then today I just swapped injectors between the 2 and 4 cylinders, and my PO304 is gone now, and I have a PO302. Which is pretty much 99% that my injector has crapped out. I have an injector on order and should be in my car on Wednesday.
I know I searched on this subject quite a bit and found my problem, but it did take me a while to figure out what to diagnose or troubleshoot. So I am hoping this post might help others in the future with the same problem. It also seems Subaru dealers are having an extremely difficult time figuring this out, but its really not that difficult. So hopefully this helps if you are having a problem with this.