The first thing to check is the SP wiring order and gap.
Duratec V6 Spark Plug wiring order

Firewall side
4- 6 -5 <--coil pack
3-2-1

1-2-3 <--engine
4-5-6
Radiator side

Spark Plug gap 0.054 inch

"Always do the cheap and easy ones first." 1996 V6 ATX 96K miles