my car turned into a lawnmower...

[confused9]

k so i have a 1989 240sx SOHC. i bought a header a couple days ago and wanted to install it. it ended up not fitting because the flanges wouldn't fit due to a shop cutting the flanges on one side of the cat and welding it to the stock header. it sounded like a lawnmower and had no power. i put the old one back on and still the same problem. i replaced the 02 sensor, spark plug wires, and gaskets on the header. i checked the plugs and the 2nd and 3rd plugs were wet. i also checked the injectors and the only one that wasn't running as strong was the third one. i can't figure out what to do anymore. i'd really appreciate if anyone could help. thanks

[chaos2000]

i had kind of the same problem my timing was off and i was only firing on 2 cylinders. i fixed the timing and everything was fine.