Nelsonmd is right on target with the fluids. Clean fluids are the life of any machine and the 4runner is a fine machine. I would do a complete fluid replacement on all systems, power steering, brakes, coolant, front and rear differentials, transfer case and a complete fluid exchange in the transmission not just a drain and fill. If you can't do this work make sure that you can truly trust the people doing it for you because it needs to be done right.
If a tune-up is in order, spark plugs, plug wires, PCV valve and grommet, fuel and air filters. I personaly use Toyota parts for all tune-ups. I am a little OCD about my maint, I guess we all have our afflictions and mine is vehicle maintenance.
Don't forget to grease the front and rear drive shafts also.