85_2fast4u

i just got my 85 300zx and i noticed hesitation while accelerating i bought a new fuel filter because the old one you couldnt barely blow through it and also cleaned the throttle body and even added fuel additive to clean injectors and pistons but still not fixed all the way and i just ordered a k&n 9 inch cone which i think will do it but if not what else coud it be please help