This is in my 2002 Legacy four-banger. The short of it is that I've changed the plugs (new NKG, gapped at 0.044), new plug wires (NKG again), and swapped in a coil from a car that didn't have this particular error, and still I have a consistent po303 and po304.
omegle discord xender
When this started, I had misfires on all four cylinders. I checked the plugs, and they looked awful, so I put in new plugs. All was well for a day or so, then the problem came back.
I swapped in a coil from a 2001 Impreza which was a good runner until its head gasket went. All was well for a day or so, then the problem came back.
Then the new wires arrived from Rock Auto, so I put them in. All was well for a day or so, then the problem came back, but now it's only cylinders three and four that are misfiring.
I'm starting to think I have some non-ignition problem which might be intermittent. What should I try next?