97 Merc Force is missing at 4000 rpms

[cellis]

I have a 1997 Merc 90 hp Force and it has been missing at 4000 rpms. I took it out yesterday and noticed it getting worse. Anybody have any ideas what the problem could be. The carbs were cleaned about a year ago. It ran fine until this year and the miss started

 

[guyjg]

You need to verify good spark on all cylinders w/a spark gap tester set at 7/16" gap. All coil sparks should be loud snaps light blue in color...orange, yellow or white spark is weak. All coils should look the same.