I just gave my 2004 nissan altima a tune up. I changed the spark plugs, changed the oil, and put in some injector cleaner which Ive done before. Now all of a sudden today I see that my service engine soon light is on and it seems that the engine is running extrememly loud even when the car is stationed, its sluggish and takes longer to switch gears while accelerating. I just had my flywheel replaced at 53000 MILES!!!!!!!!!!! It was some type of defect.... DOES ANYONE HAVE A CLUE TO WHAT IS GOING ON WITH MY CAR.