4.3 runs great except at 4000rpm

Alright, so when i first got my boat, the thing would stall out after running high rpms for a few seconds. Well, after rebuilding the carb, buying new filters, adding a inline filter, i find out that my fuel pickup was completely clogged up with junk:facepalm:. Soo after rebuilding most of the fuel system, the boat runs great...except around 4000rpm for some reason. Its almost like it hits a dead zone. It will hold 4000, but its almost like it hits a barrier and wont go past that until you push the throttle almost to WOT. And once you get past the "dead zone" the power just kicks right in. So im guessing something may be wrong with the vacuum secondaries?? I replaced the plunger in the vacuum part but kept the original spring in it