Mason240sx

so my car has been throwing 3 P0300 codes. yes, three of them at once. so i started out by replacing the spark plugs. replaced them all and gapped them. took the car up the street, i can still feel it misfiring. noticed my pcv hose was cracked where the hose connects to the intake pipe so i cut it and reinstalled it, still misfiring. i only really notice it misfiring from about 1/4 throttle until 3/4 throttle then once wide open it clears up and goes like it should and quits misfiring. what could my problem be? the car had nitrous on it when i got it so i removed the nitrous kit and ever since then it has been running funny. could an injector be stuck open and thats why it runs fine when wide open? all input will be greatly appreciated. thanks.

Mason240sx

i cleaned the mafs. still misfiring. so i started unplugging coils while the car was running and found out that when i unplugged #2 and #4 coils that the motor didnt drop rpms. so it is misfiring on #2 and #4 cylinder so i swapped the #2 and #4 coils over to the #1 and #3 cylinders to see if the misfire would change over to those cylinders (so i would know it was the coils) but the misfire stayed at cylinders #2 and #4. im thinking it could be two bad/clogged injectors.

NOLAGG

iTrader: (1)

Had the same problem , it is the injectors probably . I did a continuity test from the ecu pin of the injector and a fuse in the kick panel( forgot which one ) and checked for ohm resistance and saw how much of a difference my #2 injector ( faulty) was then all the others . Although it doesn't have to show a difference in ohm resistance to be bad I would start with that .
But injector could definitely be the cause . Let me know what happens

adrift_foolish1

Vacuum leak