I have a 2.5L '02 Legacy with just shy of 200k miles. I'm having off and on trouble with misfires (check engine light goes on/off reguarly, but when checked it says cylinder misfires). It's primarily cylinder 2, but will misfire on all cylinders. I've changed spark plugs, wires, and ignition coil, but it seems to keep coming back every so often. Previous owner said he had head gasket and drive belts replaced. Any ideas on what to check next?