I have recently done the 24x conversion on my 5.7 and now run a 2002 5.3 truck tune with the 12122156 OS. I am getting p0300 with flashing MIL every time I drive it and go above 1600 rpm.

According to scan tool I am only misfiring on cylinder 4 and 7 (roughly 4000 misfires in a 3-5 minute log on each cylinder). It idles great and I can only barely feel a slight vibration when MIL begins flashing and I am misfiring. Other cylinders mostly have 0 or less than 5.

I have swapped coils with cyl 4 and 8 to see if the misfire followed the coil, installed new wires, tried my old ckp with new crank relearn, watched wideband O2 read 14.6-14.9, seen o2's cycle between 0 and 1000mv, etc...

Is there any relationship between cylinders 4 and 7 (besides having to change the firing order on 4/7 and 3/2)? How about any known problems?

Im just looking for anything to test next.

My log file. Anything unusual going on?

diagnose24xMissingProblem.efi

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