Hi im new to the foum im looking for some help, my truck its a 2002 quad cab 4x4 4.7L it has a rough idle and the check engine light is on, when i accelerate the light starts flashing. Between 50-60 mph it starts jerkin and sputtering, when you rev it up it starts to back fire I scanned it and i came up misfire in cylinder 1,2,3,4. I talked to a mechanic, he scanned and said if i changed the spark plugs then that would probably solve my problem. I changed the spark plugs its still has a rough idle and still runs like crap. sometimes for a second it will kick in like it wants to run good. if someone out there could give me some advice on what this could be or how to narrow it down to find out what it could be i would really apreciate it thanks guys.