the other week i started loosing my top end around 5000 r[m or so and now i'm having the same problems at 3000-4000 rpm. I get a flashing engine light that reads p0300 random misfire. I've replaced wires, plugs, fuel filter and still the same. I've done some logging and i see that for the most part its cylinder 4 and 6 that are misfiring. I tried switching the coil packs around and it still is cylinder 4 and 6. anyone have any ideas. I'm starting to be at a loss as what else it could be. fuel pressure regulator is good. the only thing i can think is that it might be the fuel injectors. Can anyone help me out?