ka24e - Hesitation/Stutering at 3000-4000rpm.
First thing i did was visually check the exaust. Checked out ok.
Second was to install a new MAF sensor. Visually inspected intake and wiring for maf.
Does anyone know what could be the issue here?
Check your ignition system. Have you done a tune up recently? Set base timing.
Do what gongster said and check the ignition system… but along with that check your fuel system. I had the same problem with my old engine where the insides of my fuel filter broke apart causing unfiltered gas to clog up my injectors… if your ignition system is okay replace your fuel filter and clean your injectors whether it be with injector cleaner connected to your fuel rail or the cheap and less effective way with bottled stuff through your tank.
Hope this helps!