I just bought a 2002 forester S with 200k. Drives ok, but at idle the motor is shaking a little and the exhaust is sputtering. I ran the codes and they were initially po301, po302, po420 and po442. Previous owner couldn't pass emissions he says and gave up on her.
I cleared and drove it some more and got back a pending po301 and a po302 and that is it.
I was thinking of switching the wires from side to side and putting on a spare coil I have to start. I figure it could be injectors or valves after that. Anyone else have an opinion?