My Saturn revs very high on initial start-up (to more than 2500 rpm), then slowly comes down to idle speed in 5-10 seconds. It seems more noticeable when engine was cold, but also happens with hot engine. I serviced cooling system and replaced CTS (had cracked bulb and gauge on instrument panel only went to 1/4 mark...now falls slightly above 1/4 mark). Obviously doing this service did not correct the condition. I think the high-revving like this can be hard on the battery, among other things.
More minor: I know how to reset the lock code on the radio after disconnecting the battery, but have never learned to set the clock time. What combination of buttons does one push to set clock time?
Why? Because the engine computer will increase the idle if it notices the electrical system voltage is low. If you have a weak alternator, it can't put out much current.
Immediately after starting, your battery is a bit drained from starting. The alternator, in its weakened condition, can't put out the current it needs to. The computer compensates by reving the engine up.
Look closely at the radio. The plastic shows, in raised (but not painted) letters which are the buttons for the hour and minute.
I think that you hold in the power button while pushing the hour or minute button to advance things.
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