Hopefully you have a 14CUX EFI system. These are pretty easy to install.
The items you have to install other than the easy stuff that is already in the harness:
Intake with all its sensors (TPS, fuel temp, coolant temp, fuel pressure reg, injectors), fuel pump that will pump EFI pressure, fuel return line, O2 sensors, speed sensor, a check engine light, mass air flow sensor, etc.
If you have AC you'll have to wire that in so the engine idle will be right with the compressor running and you'll need to make sure you have the EFI resistors in place for the 5 speed (if the EFI harness came from an automatic car).
It sounds a lot worse than it actually is.
Speed sensor and getting it installed is about the only thing that is a little tricky, but it isn't bad.