So I got a 2000 Camaro z28 with only long tube header and everything else stock it ran fine no issues till recently it started running rough then at times runs fine so I took it to auto parts to use there code scanner it did pop up some 02 sensors code but I figured due to the headers but there was a p0300 code so I checked the spark plugs and seemed fine I also changed the fuel filter ran good for a bit but started running weird again any clues to what it could be?

 

A misfire could be caused by almost anything. However, on any car with headers your first suspect should always be burned plug wires.