DF 225 '2008 Drop in power

[highcountry]

Hope someone can help here. I have a 4 stroke 225 with 290 hrs on it.
Went out a couple weeks ago for the first time this year.
Day one - ran perfectly for the entire afternoon and evening (about 3 hrs)
Day two - Was cruising on plane revving 3800 when all of a sudden the power loss would go down to 3000. I could push the throttle to get it up to 3400 to just stay on plane and then all of a sudden the full power would come back. I'd go a couple minutes (with good power) and it would do it again. At one point, the power drop happened and would NOT come back. I idled down and turned the motor off, waited 30 seconds and re-started. I then had full power again.
Things that I did before going out;
- water impellor, changed motor oil & filter, new water separator
Things that I've done since experiencing these problems;
- new spark plugs, low pressure fuel filter, hooked up a remote fuel supply to rule out anything on the main tank system

I'm NOT getting any alarms

Anything else I should try before going to a service guy?

thanks in advance

[highcountry]

DF 225 '2008 DRop in power

A quick update
- went thru entire fuel system including taking apart the vapor seperator tank
- new plugs, even cycled one extra new plug thru all 6 cyls(in case one was bad
- every time I started it and held RPM to 2300, power would drop between 1 min,15 sec to 1 min,45 sec.
- I then disconnected the data wires that connect the ECM to my Lowrance HD8 (which sends engine telemetry to the sounder) Once disconnected, she's ran strong for entire 2 hr test run.

FYI just in case you experience something similar