Hi all my name is Dylan and I own a 93 2.3L NA hatch with a cool air intake, and a long tube header down to the stock gutted cats and a glasspack. The day before we installed the header, the car began cutting out between 3000 and 4500 rpm and lost considerable acceleration overall. It also now has a rough idle to the point where it almost dies but always recovers. My uncle and I replaced the MAF sensor, 02 sensor, IAC modem, and fuel filter. It seems to have plenty of fuel pressure, even with the fuel pressure regulator blocked off. Any ideas on what the problem is?

 

Really? Nobody is even gonna help me?