Fuel / Motor performance

Ok wondering if anyone knows why:

I‘be been having power issues with my 98 90hp Mariner since bought the boat. Fixed a lot of the issues and has been running stronger but still have a puzzling issue when it comes to fuel delivery.
I was running my tank empty to put all new gas in it because was thinking it was bad batch: so I’m starting to run out of gas and my motor got stronger for bout 3 secs jumped up in speed by 3mph... then After that I got an even stronger boost in power and jumped up 5 more mph for bout 4 sec then ran out of fuel. So I put 5 gallons in and go back at it, and goes back to low performance of about max speed of 18mph.
compression is great/carbs cleaned/new fuel filter and plugs and wires.
wondering if anyone would know why performance would shoot up like that runing out of gas and is that telling me something I should know?

I wonder if the float level is set too high causing the engine to run rich, as the gas was pulled out of the float bowl and the level went down to what it should be it ran better.

How would I check the float level? Pull apart

Motor ran leaner as run out of fuel ..check jets for being loose and condition of emulsion tube gasket. Reassemble with new gasket kits..

That makes sense, Should I just replace the same size that’s in there or go with a different size and part number? I’m in key west and I know that with jets you need to take in account the area and altitude. Thanks for you help.

Gaskets you replace, usually jets don't need to be replaced unless someone has been in there with a drill bit, they need to be checked for tightness. Stock jets are for sea level, smaller jets are put in for altitude since there is less air up high. Look for deposits inside the carb as they restrict fuel or air movement.