1996 120hp bogging down

I have a 1996 Force 120hp that runs good until I try to go full throttle. I can get up to 5000 rpms and can run it for as long as I want but if I try to go full throttle then it boggs down and drops to around 4000 rpms. I have checked compression--all 120 or better. Changed plugs. Good spark at all cylinders. Removed hose from carbs and cranked engine and plenty of fuel coming out. I pumped bulb while trying to go full throttle but it made no difference. Tried choking it also-no increase. Had half a tank of gas that was a little old but put in 17 gals of fresh gas. Can't believe that it would run good at 5000 rpm if gas was bad--just my reasoning--doesn't mean it is right. Suggestions needed. Did remove carbs and sprayed with carb cleaner--didn't see how to remove jets--looks pressed in. Blew everything out with air.
Thanks in advance for suggestions. Not sure what to do next.

If you can run 5000 then I doubt the carbs are the problem unless there is dirt in one?
Check/replace the filter.
Any inline connectors, remove or replace.
Maybe a different prop?

Jerry,
Would you rule out the stator? Also, could it be that the fuel pump is not keeping up with the required flow for high speed? Did try brand new gas with no difference. Took carbs off and cleaned again with carb cleaner and compressed air. Really not sure about the stator since the tach works like it should and charger gauge on the boat shows around 14 volts when going at high rpms. Really trying to figure this out. Any advice is appreciated.

Looked into the carburetor bores with a strong flashlight when you try to over 5000 RPM ?----------------Hooked up a timing light on each lead to see what happens to spark when you go over 5000 RPM ?-------------Flywheel key checked ?

Racerone not really sure what you are suggesting? Look into the carbs when trying to go over 5000 rpms on the water? Hook up a timing light? Understand checking the flywheel key but wouldn't this affect at any speed?

Sorry for suggesting some simple techniques, but good luck in sorting this out.

Some good suggestions just wasn't sure what you meant. I failed to state that the engine is on a pontoon boat and trying to do what you suggest while moving would be difficult. But the solution to this is to back the boat down at the launch with it attached to the trailer and try what you suggested.
I apologize if I sounded unappreciative just wasn't sure what you were saying.
On the flywheel key, again wouldn't it miss at all speeds?

I solved a problem with a 105 hp Chrysler outboard 40 years ago.-----------Marine mechanic had replaced the CD box and motor still ran the same.--------Buddy who owned the marina was amazed at my simple diagnoses using a flashlight.------Today is a different story I guess.

Went to a lake 10 miles away and backed the boat in the water still connected. Cranked it up and gunned it and it didn't bogg. Took it off the trailer and it never did bogg. It only reached about 5100 rpm (which was about what I could inch it to) but it ran fine. Stopped and gunned it and it took off like a champ. Was ready to use the spray bottle with fuel to spray into the carbs if it had bogged on the trailer--but didn't need to. What I did do before going out again was check the connections from the strator and they had green corrosion so I cleaned them up. Also cleaned the ground from the stator. Guessing one or both did the trick. Would have never thought about just backing the trailer and going full throttle and doing the fuel trick.Want to thank everyone for their suggestions. Bet the people at the lake thought I was nuts to back the boat in the water hooked up and gunning it. lol

Thanks again.

Running it on a trailer wasted your time.
You need to run it under normal conditions.
PONTOON!! makes a difference.
What prop? Load?
Is the cavitation plate even with the water when your running?
Or under water?
Prop size???

All the above can make a difference.