boat engine surging

evening guys

the last few times i have had the boat out, i noticed the engine surges, mostly during the no wake speeds

it seems to idle fine, and it seems to haul fine (3000 RPM and up)
when it does surge, it surges 3-400 rpm and kinda rocks to the point of me worrying about it stalling out
(it actually did stall on em twice today)



i replaced the fuel filter 2 years ago, new plugs and such at the time too

i plan to take a look at it over the weekend, or next week, any suggestions what i should look for?


it is a 1994 mercruiser 3.0 4 banger with an alpha one outdrive