My gf's 2010 subaru impreza n/a has been sporadically running rough recently. I threw an ODB on it and it's saying cyl 3 and cyl 4 misfire. It will run fine for days and then run really rough out of nowhere. In the last year I had the head gaskets replaced and I've replaced the plugs, wires and coil. It's hard to determine but it seems to happen on hot days. Anyone have any troubleshooting advice or point me to some common issues for this year/model?
Edit: I re-posted in service/maintenance as I think that's the better place for this thread. I'll try to delete this thread here. Sorry about that.
TIA