head lights,spark plugs,? converter(but we just put a strait pipe on there for now) and not sure what it is called but it goes on the spark plugs we also replaced that.but the pore car seems to be running worse. when you start it and its idling it runs good, but when you put it in gear it starts skipping and not wanting to go please help me with some thoughts on what could cause this problem bc we are stuck. thanks