Hoping someone may be able to help me out... I've been using the search engine over the past week trying to help me diagnose and fix a problem. Truck started idling rough a few weeks ago. Finally got the cylinder 4 misfire code. Started reading up on this to see if it's common. I've got a '12 TE with 160,000 miles. I changed the spark plugs at 90k.

First attempt was fuel injector cleaner and running high octane, ethanol free fuel for a few tanks, no luck. Before buying anything, I carefully inspected all plug wires for rodent damage. The wires are all fine. Today I changed out cylinder 4 coil pack and spark plug. Cranked her up, same code and rough idle.

I'm now stumped, does anyone have suggestions or is it stealership time?

I suspect that you already know the next step.... check the injector wires for damage ohm check the injector and swap #2<>#4 injectors if nothing found in steps 1 and 2.
If you have the right test equipment then check the pulse to the coil pack and the suspected injector.
If you have to have to take it to someone, a good diagnostic shop is usually $uperior to the dealership.