[A34] 2004 maxima power loss in 2500-3000rpm range

[mb76pl]

hello all,
so, I'm struggling with this problem for a while now
the car is 2004 maxima, the symptom - power loss at very specific rpm range. Very reproducible - each time i put my foot down the gas pedal, car accelerates smoothly until it reaches 2500rpm, then it looses power (it's like I took my foot off the gas pedal half way) it accelerates poorly till ~3000rpm, then the power kicks in again and it accelerates correctly till red.
The car is stock, except for Fujita CAI. Fujita sits there for few years, problem started around half a year ago.
What I replaced so far:
- throttle body
- MAF sensor
- spark plugs

what I checked:
- vaccum's ok
- air filter clear
- engine ground connectors cleared
- injectors ok (according to consult)

no errors from ECU

how to diagnose this ? anyone please ?