Look at the oxygen sensor values for the left and right bank along with the fuel trim values for each bank. If the right bank (cyl 2, 4, 6, 8) oxygen sensor values are consistently rich and not oscillating to lean, rich, lean, rich, etc and the right bank fuel trim is consistently negative and constantly taking away fuel, then the problem lies with injectors 4, 6, and/or 8. If one of those injectors is leaking and adding excess fuel, the oxygen sensor feed backs a rich signal to the PCM for the right bank. The PCM will reduce injector pulses (negative fuel trim) for cylinders 2, 4, 6, 8 and try to get it to a lean condition and oscillate between lean and rich. Sometimes the PCM cannot correct sufficiently and the lean condition on cylinder #2 will cause a misfire.. . . So, the past week about i have been having an issue with code p0302 (cylinder 2 missfire), currently got 298k on the clock. Had p0304, p0306, and p0302 and ran a little rough and a bit shakey, checked the sparkplugs and they where pretty worn for 20k ish on them, replaced them and it resolved the other missfires and the missfire counter's where at 0, ran fine, . . . .