Sr20det misfire/hesitation under 4k rpm

[jduke]

Above 4k rpm she rips hard no stuttering/misfire/hesitation, below 4k rpms it does all of that. Swapped a new o2 sensor(oem) and new spark plugs (bkr6e). looked over for boost leaks as well found none. I Just imported the car 90 180sx so im finding all the mods as i dig in. Where should i start next
Here's what i know it has so far.
Swapped to a red top SR
z32 maf
Trust FMIC
Power enterprise turbo
3" turbo back exhaust
Has a different ecu from "Technical shop ADVANCE original SPL ROM MT2000 real time rom emulator map tracer"

[RoastedBumper]

Try checking all of your coil packs with a multimeter.
I recently had an issue on a ka24de with those symptoms, drove fine for me above 3K but horrible misfire/bogging under that. Turns out my ignition coil resistance tested bad, despite plugs still sparking.

[jduke]

Got the issue resolved. It was either my maf or knock sensor/harness. Replaced my z32 maf with a known working one and also a put a new oem KS and wiring specialties harness.

[jr_ss]

Generally those are Maf related issues. Try cleaning the old one and swapping it back in.