quick tune up question (just got a 91)

i just recieved a 91 sedan deville, 120 k miles. what are some maintence things i should do to get this thing running solid. the previos owner i dont think took care of it too well.

i was thinking of maybe
fuel injector service
new spark plugs
fuel filter/air filter
oil change/filter change
trans oil and diff oil
get the timing check (is this necessary ?)

i was thinking of doing it myself or should i go into a mechanic and say tune me up.

i was thinking of maybe
fuel injector service
new spark plugs
fuel filter/air filter
oil change/filter change
trans oil and diff oil
get the timing check (is this necessary ?)

i was thinking of doing it myself or should i go into a mechanic and say tune me up.

That's a good start. I'd also replace the spark plug wires, cap and rotor. I'd check the timing, it's easy to do.