My 5.7L started missing

My 5.7L started missing when it is under a load or RPMs are greater than 2K. It starts and idles fine. This all started after the fuel pump went out and was replaced. It seems to get worse as the engine warms up.

Might check the fuel pressure. I wonder if the "new" fuel pump is faulty and the engine doesnt get enough fuel when it needs it above idle. Good Luck

Fuel pressure is ok

My 98 with the 5.7 has this problem . It has been diagnosed as weak valve springs. I went through the entire ignition and fuel systems first. It seems the weak springs are kinda known in the dealer service departments.

Did the valve spring problem, happen all at once? I have also noticed that if I remove the black box that says vortex from the throttle body the engine won't run, it will run with it on it just misses. This is with the engine warm I don't know about cold yet.

bad plugs / wires / cap and rotor can cause a mis under load conditions

Changed plugs, wires, cap and rotor?