2004 Mercury 90 3 cylinder surging

My motor idles like a champ, runs fine for a bit and then if I try to push it much past 4k rpm it will begin surging back and forth between 3k-4k rpm. I have replaced the tank to engine lines, bulb, the fuel water separator, the inline filter, and the spark plugs. Before changing the plugs i ran the engine off seafoam for a while and did a deepcreep treatment through the intakes. I assume it’s a fuel restriction. where do i start now? time for carb rebuild?

Try squeezing the primer bulb while its surging and see if it goes away.
if it does, you have a fuel pump or a fuel line issue
if that doesn’t help, while its surging spray some fuel into the intake and see if it increases in rpms.
if it does you most likely need a carb job.

www.teamcharlestonmarine.com
www.bombislandboats.com
IF I RESPOND IN ALL CAPS, ITS NOT ON PURPOSE, AND I AM NOT YELLING