So I have a 2007 Formula 400 ss with Mercury 525s. Beginning of last year my starboard engine would run 200 rpm down until about 10 minutes of cruising than the power would kick in like someone flipped a switch and rpm would be perfect for the rest of the day. During the year it seemed to take longer and longer to kick in per say. Well this year it will not recover so I have changed the plugs (all looked fine) checked the plug wires and they seem fine. Can someone point me in the right direction. I am leaning towards the coil pack but looking for some one with experience. My boat mechanic is a few weeks out and would like to try and fix it now..

Thanks for any info you can give.
Bob

engine scan if all possible with Merc G3 and inline seal spark checkers to see about firing events of the coils ( spark ) Next fuel pressure checks - thru out all rpms that are there currently .

compression test