'94 200 Mercury missing

[garbubba]

Had a great day out on the boat today, ran 25 miles out (&back!) but when I slowed at the launch she was missing, not like i've heard before. It was irregular, not one cylinder I'm pretty sure, no smoke. Put it up & brought it home, when I flushed it it was still missing, not bad, but missing

Where do I start to trouble shoot this one?!

Plugs first?

I've been through the entire fuel system recently.

Replaced both power packs two years ago.

Thanks in advance,

Doug