ka24de hesitation help about to kill myself

[s13whore]

ok so like the title says i just bought another ka cause my other one had bad bearings so I installed it and it drives fine but when I floor it, it hesitates to pick up speed but if I slowly put my foot on the gas it starts taking off I dont know what it could be, also when its idling if i tap the gas quick it seems as if the rpms go down then up. So far ive replaced my coolant temp sensor, my whole engine harness, my mafs I dont have any vacumm leaks or exhause leaks already checked my cat is hollowed out, replaced my o2 sensor, has new fuel filter, new spark plugs, new wires, all grounds are connected, the motor doesnt backfire or anything idles perfectly, idk if it could be the distributor or the back of my exhaust is clogged need help im tired and dont know what else it could be my fuel pump is good once floored it just sounds loud and doesnt wanna go anywhere it has headers with stock exhaust idk if that could affect it in anyway any help is gladly appreciated thanks.