04 Montero Sport 3.5L 4WD
P0305 a couple weeks ago, started after warm-up. Popped up after fighting through EGR insufficient flow, which has not come back. I swapped coil 1 and 2, and the code remained at P0305. Next step, swapped plugs between 5 and 1 (since those are the easily accessible plugs on this thing). Instead of the code moving from 5 to 1, as I'd expect, I now get a P0304. Very strange! 1 and 4 do share a coil, but I swapped coils, again and it remained in 4. So, I replaced the plugs in 1, thinking maybe it was somehow shorting when 4 was fired, but no... just remains a p0304.

I hate chasing rabbits that don't make sense, but any clue as to why I'd get a misfire swap to an even side cylinder when swapping plugs between 5 and 1?

Thanks for any help.