The throttle accelerator pedal on my '92 Saturn SL2 seemed to be sticking so that when you stopped at a traffic light, the idle rpm might be at 2-3K before slowly dropping back down to idle speed after 30 or 40 seconds. The pedal and cable linkage were fine. The 'Service Engine Soon' light did not come on. Googling the problem suggested that the the throttle body might be gummed so disassembled and cleaned it but the problem was still the same. The throttle body had a little solenoid valve and piston attached to it that opened and closed a little bypass hole around the throttle body butterfly valve. Turns out that is the 'air idle control valve' or AICV and it adjusts to control the flow of air through a little hole about 1/4" in diameter that provides the air to the engine for idling when the throttle butterfly is closed. I didn't think it could be bad because there was no fault code or SES light but I decided to change it as there wasn't much else that could be causing the problem. Et voila! The problem was solved.
What puzzles me is why there wasn't a fault code for the AICV function. My guess is that the Saturn doesn't throw a fault code if the idle rpm doesn't drop back down like it's supposed to perhaps because the programming is set to maintain MINIMUM idle rpm and only issue a code when the idle rpm is below that. At higher rpm, the throttle butterfly is supposed to be open and the AICV closed but the computer has no way of knowing that the AICV was failing to close. The computer should have thrown a fault code when the throttle position was closed and the idle speed was too fast but the car is a manual transmission so the rpms stay up to correspond to the road speed even when you back off of the gas so the computer didn't know the car was 'idling' rather that 'driving.' The computers on newer OBD2 vehicles know what the vehicle speed is but apparently the OBD1 Saturns don't report the vehicle speed to the computer.