I have a 2003 Expedition with the 5.4 engine. I went out to start it this morning and it ran rough and the Service Engine Soon light started blinking. This vehicle has run smooth as silk from the day I bought it new. I had returned from a weekend trip which was about 1000 miles round trip the night before and everything was fine. Then this morning, it idled and rough with the light blinking. Another interesting thing is, I had the oil changed last Friday and they mentioned my battery was low and should be replaced...but the battery "seemed" fine as far as starting the vehicle etc .... Could my issue be a bad coil pack? The thing that puzzles me is it happened all of the sudden.