45 hp evinrude commercial running bad

Hi I have a 1990 Evinrude 45hp commercial engine. I don't know much history on it besides it local fire departments engine did not get much use. I recently bought it after it had sat for a few years. First time out it acted like it was hitting the rev limiter at lower rpms then it straightened out and ran ok but did not seem to have the top end power it should have. First I installed new plugs and cleaned and rebuilt both carbs both were very clean in the inside and showed not sign of a cause of the issue. I took it out after and the boat ran great for about the 20 minaute sea trial. Went out later that day and engine had no power and seemed to have a miss fire I had extra new omc coils so I tried both no change. After that I found an article about the power pack having the slow mode so with the previous symptoms 2 of them could of been a power pack issue so I replaced the power pack. First sea trial after engine ran great took it on a second about 10 minute sea trial no issues. Let it sit for about an hour and went back out and same issue no power if I pump the primer it seems to want to pick up rmps then drop off. Fuel ball stays tight when issue is happening, unhooked temp sensor wire no change, took carbs off and rechecked no issues found, engine has 120 psi on both cyclinders. Any help would be greatly appreciated.

would suggest testing over heat alarm, disconnect wire at sensor and ground to block, with key on does alarm sound?
is power pack still under flywheel? would also suggest getting a rebuild kit for carbs. Is the VRO still in use? all this is just more back round info.. rope start or electric start?

It is a rope start. Both carbs have been rebuilt and taken apart and rechecked. The engine does not have a VRO dont think it came with one. Power pack was just put on new sierra and is still under flywheel. I unhooked the wire dont think this engine was equiper with a alarm. This system has no battery.

will my experience is with electric motors. looking at parts break downs, think rope starts didn't have VRO's. pumping primer shows improvement, maybe fuel pump,(shop around prices very greatly), also check fuel filters not clogged. is portable fuel tank vented?