40 ELN Cutting out

ive recently replaced the oil pump and cleaned the carbs. ran fine for the first few minutes running at 3/4 throttle. several hours later i went to 3/4 throttle and it kept cutting in and out. felt like i was letting off the throttle. once i did let out on the throttle and got back on it, it would run fine. do not have a tach so im not sure what rpms it is cutting out. does anyone know what this may be? i plan on changing the spark plugs and the fuel line this week.

thanks,
jason

[boats.net]

Could still have trash in carbs or ignition problem, check to see if firing on all three cylinders.