Could be many things, have a serial number?
Is this a new to you boat or has it just started this issue?
How high do the RPM's go up to at WOT?
What has been done this year and last to the motor so far as maintenance?
Define the word lags? Do you have access to a fuel pressure gauge? When was the last time you had a tune up? Does the engine "bog" or does it "stutter".
Boat is a 2006 Sea Ray 270.
It’s a new issue started in late June.
It gets to 3500 rpm ok then takes 30 seconds of time to get up to WOT. Once planed out it seems to be ok.
New plugs and wires August 2016.
No temperature or oil pressure issues.
New replacement of the lake water pump impeller in May 2018.
Launched May 2018. No noticeable excessive scum. Run it at least 2-3 days a week all summer in Pretty clean lake Michigan water.
2006 Mercruiser 6.2L MPI Horizon Bravo3
S/N: 0W373955
Model No: 4-R4203HT T
Goes to 3500 RPM then lags getting to WOT.
It’s a new issue started in late June.
It gets to 3500 rpm ok then takes 30 seconds of time to get up to WOT. Once planed out it seems to be ok.
New plugs and wires August 2016.
No temperature or oil pressure issues.
New replacement of the seawater pump impeller in May 2018.
Launched May 2018. No noticeable excessive scum. Run it at least 2-3 days a week all summer in clean lake Michigan water.
Suggest the distributor cap, they can cause issues and look good. Many have failed and provide no sings of visual issue. If it doesn't fix the issue its a good thing to have a spare in the box. Then check fuel pressure