1998 Saturn SC2 has been frequently stalling out.

First remove the throttle body. Then locate the Idle Air Control Valve and the 2 TAMPER-PROOF TORX screws that attach it. Soak with WD-40 (or equivalent) and use the correct size TAMPER-PROOF TORX bit on your ratchet and remove the screws (make sure not to drop them--they are NOT magnetic). Mind the large O-ring that seals the IAC to the throttle body; don't damage it because you will need it for the new IAC* (* if you don't buy GM replacement parts). While you have the IAC out, spray the **** out of the throttle body and clean the throttle plate with carb spray, a rag, and a old toothbrush(I'm serious--EVERY GOOD MECHANIC HAS ONE). This will break up the carbon and gunk collected over the years and mileage. Once you have a nice, clean, DRY throttle body (*dry is important because carb spray will expand the O-ring on the IAC and it will split or break the seal--which causes poor idle*) lube the O-ring with some White-Lithium grease (spray some on your finger tip and apply) and firmly press the new IAC into place and reinstall the screws. Reinstall the throttlebody and reconnect the hoses and wires. Crank the vehicle and let idle for at least 10 minutes so that the computer can relearn the new IAC positioning. (this is because the old, faulty IAC was sending poor signal to the computer and the new one must be seen to take orders from the computer)
HOPE THIS DOES THE TRICK, SINCE YOU DID NOT ASK HOW TO DIAGNOSE THE PROBLEM.
Mr. Goodwrench