Help with 200hp merc running rough.

[CharlestonSC]

1992 200hp black max.
Just got it in the water today first time this year.
Mods I did this winter.
Added 2nd fule tank, but have not used it.
changed stator and voltage regs, they didn't go out on me but the few windings were loose so I replaced it before it fales me.
Did power packs last summer.
It is running rough, pulled wires off when running and no change or not much if any change when I pull off the bottom left and bottom right spark plug wires.
you can for sure tell when I put the other 4.
Idles a bit rough but not to much different that it ever ran.
But won't get above 4K rmp and it sound like it's missing a few cylinders.

Any thoughts where I should start???,

Spare I'm in MT pleaseant have any time to check it out?
Thanks