how exactly the individual throttlebodies work?

[CA18 RS13]

i have a problem that has been annoying me for a while now. below 4000rpm my car is slooow. not just somewhat slow i mean beat by civic DX slow then exactly at 4000rpm it kicks you back hard. this happens in every gear, making it so i either have to maintain the current speed, or while accelerating drive really slow(and obnoxiously loud while not really going anywhere) or be accelerating into the back of the car in front of me. the cause of this has to be the intake manifold, there is no other explaination. the engine feels like it is choking on itself in lower rpms, i can feel the car struggling to accelerate like its wading thru quicksand, then at exactly at 4000 it breaks free. i am hitting full boost of 0.75 bar before then and it doesnt jump up or anything after i am able to accelerate freely. i know of coarse that ca18 has individual throttlebodies, but ive heard a few different ways that people think the intake manifold and throttlebodies work, so if someone could clarify it for me that would be great

[Movingviolation240]

it's not individual throttlebody's, there are 8 intake runners, and there is a plate that blocks 4 of them off at low RPM's. Then as you speed up they open. This is to keep the velocity up on the intake charge so you get better low end grunt.

If you want to test to see if it's them just find the vacume diaphram on the end of the intake manifold (it's hard to see cuz of the firewall but it's there) and pull the vacume line off it. Then drive it and see what the car dose.

Other problems could be the timing, TPS, or just your plugs getting dirty and the car surging. Also have you checked your cam timing lately?

I know I delt with that same problem like a year or two ago but I can't remember what exactly I did to fix it, sorry I can't help you anymore.

later,paul