mustangsvo85

i've got a 97 dx coupe with a 5 speed. around 150k miles. I've replaced the the ignition coil, spark plug wires, spark plugs, and fuel filter. I have an aem intake, header and exhaust with no cat. I'm only running codes for no cat. I have a hesitation when driving that seems to come and go randomly, basically feels like I lose 10-20 horsepower then it comes back randomly. this happens everywhere. going up hills it feels like its missing and I have to floor it to make it to the top of a slight grade. has anyone had issues like this? I can't afford to go replacing stuff blindly on my budget so narrowing it down would be best.