Q: alternator on 1993 Mitsubishi Expo LRV

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I own a 1993 and having difficulty with my battery going dead with the charge light on in the car. I've checked the alternator and it is in good shape. the connections are good to the battery and all else seems to be ok. I cannot figure this one out. also, when I put the car into park after driving it, the idle will go up and down.
(2) Answers
If the charge light is on and the battery is going dead, then the alternator is not charging. This is probably due to an alternator or wiring problem. The issue should surface during a complete diagnosis of the alternator/charging circuit.
my 1993 expo was similar. They said air mass sensor and/or throttle sensor. Finally another place found a bad O ring to the distributor and oil in there with the parts in there. $800 "tune up"(distributor, plugs, wires, points, etc). Still sometimes revs up a little. Still might need the other two things.