hesitation under 4k rpms

i have a 83 kz750-n2 the bike has a hesitation anything under 4k rpms, once it hits 4500 rpms and up its a rocket, and very smooth. It feels like turbo lag on a car, if you easy the throttle is decent acceleration but if you got WOT theres lag until 4500rpms. Ive cleaned the carbs, has new carb intake boots that goes from head to carb,new plugs. any suggestions ? possibly carbs out of sync or something? any help would be appreciated. thanks

First thought to come to mind is Needle/clip position on the lean side....

Pre-carb cleaning, did this condition exist?

Have you synced the carbs recently?

Have you just recently switched over to different exhaust, pods or something else?

What are your plugs telling you?
Meaning, condition, rich, lean, sooty, oily etc...

Ignition timing spot on?

OMR

Running pods or low restriction baffle in the muffler? That will make it run lean.

the bike is all stock, only 7400 miles on it, never modified, so im guessing the carbs have never been re synced,ran the same before the carbs were cleaned. Will pull a plug and see what it looks like.

Remember, everything from airbox to exhaust has to be air tight.

Clean air filter.
Seafoam!
mixture screws,
sync carbs,
timing.