2014 mercury 115hp EFI 4 stroke running rough, lack of power

I've been troubleshooting issues with this engine, and found a problem with the low pressure fuel pump and have that fixed. On my test run the engine now has consistent supply of fuel, but is running very rough above 2000 rpm, and barely has enough power to get the boat on plane. At wide open throttle it will slowly get up to around 4,000 rpm, seems to have about half the power that it should.
I had a fuel pressure gauge on it and had over 50psi so don't suspect a high pressure fuel pump problem.
While idling, I unplugged each of the 4 coil packs while running and each one made the engine run worse, so I don't suspect a single bad cylinder.
I'm wondering about fuel injectors, spark plugs, and coils. I have a new set of plugs to throw in, but would like to test injectors and coils.
Does anyone have specs to test injectors and coils with multi-meter? What should the resistance be on these?
I've been told a service manual might have this info but don't have one.
What else could cause this lack of power?

Thanks for the help!

Does the motor have adjustable rocker arms ?
Do the correct verified sparkplugs first. Do not assume the ones in there are the correct numbers.

I don't know about adjustable rocker arms, how can I tell?

I'm helping a friend with this boat, I put the spark plugs in last year. Bought the same replacements that I believe are spec'd for this engine which are NGK LFR4A-E. I'm going to put those in next and test it.

Does anyone know specs to ohm out injectors or coils?

I've been doing some reading and symptoms sound like one possibility is the main ECU is bad, sure hope I find the problem somewhere else.

Thanks again