My Forester (1999, 125,500 miles) started acting strange last night. On my way home, it felt like it was losing power, then felt like a cylinder or two were misfiring, then started sputtering and stalling. Luckily, I was able to make it home. Diagnostics told me that three of my four cylinders were misfiring, so I purchased plugs & wires, hoping the problem wasn't with my fuel injectors. After replacing the four plugs, everything was working fine. It started right up, the engine ran smoothly, the code was gone, and acceleration was great. I drove it to the auto parts store to return the wires that I obviously didn't need, and when I was nearly back home (~10 mile round trip), the symptoms started again while climbing a very small hill. Loss of power, some engine lurching, check engine light flashing, and wanting to stall.
I haven't checked anything since I arrived because I wanted to consult the Subie crew first. If the new plugs have failed already, could a major engine problem be causing this? The plugs that I replaced only had 17,000 miles on them. Also to note, when I first pulled the boots, I noticed some oil near the top of the rubber in cylinders 2 & 4. Please let me know if you have any suggestions. I hope my baby isn't dying!