Had to make a trip to the city tonight, on the way up had flashing SEL so I stopped by Advance Auto and had a code scan done. Came back multiple cylinder misfire,they thought it could be the coil packs('99 4.6L) Had it checked again when I got back home at Autozone and it came back as code 0302 misfire cylinder #2, which one is it ??? I just put new plugs and plug wires on last fall.Plugs are Motorcraft double platium and wires are motorcraft oem replacement. Truck is a '99 Expedition 4.6L 96,xxx miles.

 

Sounds like you need to replace the coil packs. They're usually good for about 90k mi. This will cause a misfire and would explain why it's doing it even after replacing the plugs and wires.

 

could also be clogged injector

 

Been there / done that - I'd vote for a bad coil pack.

 

If that truck has the coil on plug setup then I agree with the others. If it has a regular coil pack setup like my 98 has, then they last forever (usually)

 

With all due respect to JustinH, the coil packs on your 4.6 DO wear out. Like gkbid, I've "been there / done that". I've replaced them on at least 40 Ford trucks with the 4.6 engine, and on average, they are good for about 90k mi. I've seen some get over 200k on them, but not many. On my personal truck ('99 F-150 w/4.6 Romeo built engine), I had to change them at 75k mi. This is a VERY common cause of misfire in the 4.6 engine. Listen to the guys at Advance and change them. They're usually about $40-$50 each. It's very easy, and you can even do it in their parking lot in less than 10 minutes, or get a set of ACCEL for a little more $. You could get off cheap and just replace the one coil pack just to verify if this is the problem, but you should probably replace the pair. Chances are that the other will die soon. Although I can't tell you for sure if this is your problem without looking at the vehicle, I would almost bet it is. Coil packs deal with a lot of heat and the individual coils inside them do wear out just as often as the coil on plug (COP) setup.