40hp Jet idles and runs but can't get rpms up

[Phillycyclocross]

So as the title says, I'm having issues with my boat motor. Bought a '94 Bass Tracker last year that has a 40hp jet on it. So far I've done the following to try and fix the low rpm issue:
Rebuilt and cleaned the carbs (3 times new jets. Everything reset to factory spec), changed all fuel lines, rebuilt feul pump, changed all filters, checked compression (120ish on all 4), new spark plugs, new wires, 4 new ignition coils, emptied fuel tank and replaced with all non-ethenol gas.
I believe that's it but there may be more. After all that nothing changes. I fire it up and when I hit the lake I get maybe 2500 rpm and with the throttle buried I'm barely moving. At a loss. Any suggestions would be helpful. Thanks

 

[CaptnKingfisher]

Sounds to me like your not running on all cylinders. I would try reading the plugs if you've got an eye for that to see if you've got a dead cylinder. Or use a spark tester and see if all cylinders are getting strong consistent spark (use an adjustable spark tester and see if spark can jump 7/16" for all cylinders). Just my guess but its an easy place to start

 

[CaptnKingfisher]

I just remembered another test you could do. Cylinder drop test. With the engine running use insulated pliers to remove one spark plug wire. Rpms should drop but engine should continue to run. Shut it down, put the spark plug wire back on the plug, then start the engine again and pull the plug wire for another plug.. do this for all the plugs. If during this test you remove a spark plug wire and don't observe a drop in rpms then you've found the cylinder that's not firing. Make sense? Different way to skin the same cat