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Is the check engine light on or flashing? Which coils did you replace? Did you use Ford coil and plugs?
When the engine light is flashing the engine has a cat damaging missfire and really should not be driven far while missfiring. You should go to your local parts store or autozone as they will scan your truck at no charge. Once you have the code numbers which may look like P0301 let me know what they are so we can proceed with the diagnosis and repair.
If you have the codes read and you have missfire codes (P0301...P0308) then I suspect faulty coils and plugs. If the codes are P0171 and P0174 then you should check the PCV tube.