i gave a 2012 civic si coupe its full bolt ons nitrous tune stage 4 clutch a d flywheel. after installing the clutch and flywheel i installed a bigger fuel pump in i took the car for a drive it drove perfectly fine for like 10 minutes or so than it started misfiring the check engine light started flashing. than i came to a stop than the check engine light went off than when i would start again the car would misfire around 3 grand and would not go anywhere. i took the bigger fuel pump out thinking that was the problem but no it still does it. i got new spark plugs that wasn't the problem eather. i have no idea what could cause this she drives completely fine than it will start misfiring all of the sudden. and i tested the check engine light it had 5 codes on it cyl1. cyl2. cyl3. cyl4. misfiring than the fifth code was multiple/random cyl. misfires? PLEASE HELP.