Mitsubishi Repair: 94 Diamonte idle problem, speed controller, throttle body

Question
I drive a '94 diamonte v6 automatic.  I recently had the throttle body cleaned because it would die every time i let off the gas.  Now it is running better but it still sputters out occasionally, and more so if i turn the a/c on.  It idles at about 5k/rpm.  I wanted to know if that is about right or if I should adjust it it a little.  Most cars i have owned usualy idled at about 8 or 9k.  I would check the manual but I live in japan so I cant read it.  Any help you can offer will be greatly appreciated.  Thanx

Answer
Matt,
Most automatic transmission vehicles idle around 800 rpms (not 8k-9k).  If you actually mean your engine is currently idling at 500 rpms, that is too low.  If the car seems to idle fine once it reaches normal operating temperatures, that may indicate your Idle Air Control motor (IAC) could be malfunctioning.  It's also known as the Idle Speed Controller (ISC).  This device, which is attached to the throttle body, is responsible for maintaining a constant idle speed.  When the IAC starts to malfunction, it may bounce between a high idle and low idle, and could cause the engine to stall.  Do not try to adjust the idle speed until you are sure the IAC is in good working condition.

Another possible problem could be a failing alternator.  When the alternator starts to die, your idle will become lower and can cause your engine to stall.  I would recommend having the battery and alternator checked out.  Also, replace your air filter and fuel filter if they haven't been changed in more than 2 years.  I would also recommend replacing your spark plugs and plug wires if they have been on the car for more than 30,000 miles.
Good luck!