Tail lights, running , interior lights out, where is the problem

check your fuses to begin with then you could try swapping around relays in case one is going bad. The best way to find the problem is to concentrate on one circuit in particular like the tail lights, i would trace the entire circuit looking for issues most likely they are all related it could be something as simple as the switch that controls the headlights.

Check to make sure the actuator for your 4wd is actually actuating not just hearing it also check your 4 wheel drive unit fluid for debris in case its damaged and the reason its not engaging, most likely if its electronically good it will be mechanically bad.