pull my hair out

[michelin man 53]

I have a 1998 expedition with a 4.6 with the 2 coil packs. periodically it will start running rough at idle or when you first give it gas . I have had it scanned and it showed o2 sensors and miss fires on 3,4,5,7 . Had a old tec at the local for dealer tell me to put new wires on it Before spending a fortune on everything else. The wires fixed the problem. But its doing it again. The wires I put on it were the factory set . What could be causing it to repeat the same problem. Wires are 8 months old ford Motorcraft. Any help will be greatly appreciated.

 

[Mediamonkey11]

Plugs and wires are always the first I'd go with. Go for plugs I say!

 

[98EXPnSRQ]

Water can get down the head into the spark plug wells and cause a misfire. You can try removing the plug end and blowing out the hole and wire boot. Use lots of dialectic grease inside the boot on the connection. If you plugs are old, I would also change those as mentioned.

 

[black 4x4]

Sorry if I missed it in your post but you said you changed the wires but not the plugs or the coils? If you didn't changed them in near past or ever, there is your problem.
Truck is 1998. It's time for new plugs and coils.