Do the easy, cheap things first. Remove the idle air control motor and soak it out with throttle body cleaner. Shake it around until it sounds like it is starting to fall apart inside. Pour out the dirty and black cleaner and remount.

Then clean the throttle body. Just take off the intake hose and spray cleaner on the butterfly valve and remove all of the brown/black gook. Make sure you open the butterfly and clean the back side.

Then look around for vacuum leaks, the hoses are all 14 years old.

Last, suspect the MAF. It costs money to replace.

Klaus
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My advice is 2 cents, so you got what you paid for...