Where is the engine control module?

Where is it located?

Usually on a Ford it bolts under the drivers side dash and extends through the fire wall close to the fender.

Is it necessary to change ecm after changing all six coils? I didn't have any fire to the #4 cylinder.

YES and you must get one with the primary eeprom # 7463-fmc-19-aee1 or it'll never run again!

It is mounted under the hood on the fire wall just under the center of the windshield with a bunch of wires going into it. I'm about to rip mine out to replace it and my coils. Apparently the coils and the pcm can be mutually destructive but I'm not sure. I do know the motor craft coils last a lot longer though.