a misfire is a hard thing to track down. I'm having the same misfire and I've been working on mine for a while. I would swap you plugs/ wires/ injectors and see if it follows the change. If not, find a place with a OBD II reader that can do freeze data and find out when the misfire is happening. It can be a number of other things like, bad cat or O2 sensor, timing, knock sensor, valve lash, or burnt valve but usually those will cause multiple codes. I have cams and a LW flywheel and crank pulley so i always thought that was my problem but it may have just been masking my actually misfire. After i did my 6-speed swap and put in a heavier flywheel all the misfires went a way but the p0302, so i may have had an actual misfire the whole time and didn't realize it.