You would need to know the voltage/resistance parameters for the TPS and IAC. Try putting a voltmeter across the various terminals and see if the resistance changes smoothly, or if it's jumping around alot. IAC is generally controlled by the ECM by altering voltage/pulse duration, usually motor or solenoid activated, and neither is likely your problem.
Easy way to check for snapped timing belt is simply to crank the engine over, and if it spins much faster than usual, it's cause the resistance offered by the valvetrain is no longer there. Not sure what engine was in these Olds, but if it's a six cyl, it's likely got a timing chain, not a belt, and these almost never fail. Sounds more fuel related to me, or very bad spark issue (failing coil, primary). Hope this helps.