1995 3.0xl Mercruiser Alpha 1

[Jgrinds68]

1995 Regal Valenti 182, 3.0xl alpha1.
Bought this boat end of last season. Boat runs goods, but engine flattens out at WOT. If I pull the handle back about an inch the RPMS goes up a little and the engines picks up a little maybe a small change in speed.
Did a full tune up, plugs, cap, rotor, wires, ran a can of seafood through. Engine has more power, but still the same thing at WOT.
What should I check?

 

[Rick Stephens]

Since pulling throttle back causes the change, rebuilding the carb seems the fix.

 

[Alumarine]

What revs are you at for WOT?

 

[Jgrinds68]

When I noticed this I was around 4100 RPMS per the dash gauge. 4 adults on the boat.
The boat didn't seem to not be picking up like I thought it should. So I started pulling the handle up, and when I got around am inch up, the RPMS jumped about a 100 and the engine seemed to pick up and feel like it had more power. I pushed it back down and you could feel the power die

 

[Jgrinds68]

My original thoughts are timing, and to see if it is advancing as it should. It could be the carb, but it could be a lot of other things also. Knock sensor retrading the timing or keeping it from advancing, and such. I was hoping someone else had this problem before and could let me know what they found.