whatcould be causing the misfire

You may have a crack in the ignition coil ... or Plug wires .... Open the hood when it's dark .. start the engine and have a friend Rev it up ..and you can sometimes see where the sparking is coming from

I would say you have a bad coil. There is a coil on each cylinder and if they are going bad you will get a misfire. Once it gets bad enough the check engine light will come on and tell you which one it is. Never wash a Ford Triton engine as the water ruins coils.

Likely a bad coil or a plug wire boot has a small hole burned through it due to the high voltage to the spark plugs. If it hasn't been done I would replace all spark Plugs, plug boots and coils. Make sure you use genuine Ford coils or you risk having more problems. Some of the after market coils don't work for long in Fords.

I replaced the plug wire and still no power to the plug

I get power from the coil pack but not to the plug