P0300-multiple misfires-07 M35

[JoserMac]

Hello, I have a 2007 Infiniti M35 that recently started misfiring. I first changed the sparkplugs as they were well worn and only replaced by the previous owner who knows how long ago. Upon inspecting sparkplugs found in in sparkplug tube, So I ended up replacing both valve covers as well. Still misfiring after starting car back up. I also replaced the coil packs knowing that was a possible cause of the misfiring. What else should I take a look at before I get this thing checked out by someone else. Can it possibly be a fuel pump issue?
Thanks for taking the time to read this.

[Ilya]

Are all six cylinders misfiring? If not, does moving the coilpacks around move the misfires around? I have heard of new coilpacks being fault.

Could definitely be fuel too...

[JoserMac]

Im not getting an exact cylinder misfire code. I tried moving the coil packs around to no luck. Its just the P0300 multiple misfires failure. I had the chance to use a friends scanner that's a bit better and the lights indicating Catalyst (CAT), Evaporative system (EVAP), and O2 sensor (O2S) were red and blinking.. My next best bet was to replace the O2 sensors and see if that would be the cause.