Before replacing anything, has the check engine light come on? It could be a throttle position sensor (TPS) or idle air control valve (IAC) or as simple as a vacuum leak. Without a check engine light and trouble code, it becomes a guessing game.
Take the car to a nationally recognized parts store if the light is on and have them scan it. Most will do it for free.
As far as a tune up, spark plugs, plug wires, distributor cap and rotor. I usually like replacing the fuel filter and checking the air filter and PCV valve.