Engine is missing or miss-fireing on 1998 Ford Expedition

I am having a problem with the engine missing. I replaced all the coil packs, intake gaskets, mass air flow sensor and spark plugs and its still having a problem. My next thing is the e.c.m wanted to know if that would be a good next step thank you for your time,
Tom Finnell

1 answer
Who's looked at the truck already? What codes is it setting? Stop throwing parts at it and get some diagnostic work done. You'll thank me later.