Low idle in park, rough idle in gear, stalls at stops

Old! What do you mean "old"? My daily driver is a rusty trusty '88 Grand Caravan!

If the battery was recently disconnected or run dead the Engine Computer lost its memory and has to relearn "minimum throttle" before it will know when it must be in control of idle speed. The engine will be hard to start unless you hold the gas pedal down 1/4". It also might not give you the normal "idle flare-up" to 1500 rpm when you start the engine, and the engine will want to stall when coming to a stop. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

I guess I was mostly describing the level of upkeep. There are several problems beyond this but running properly is my priority of course. Anyhow, I really appreciate the advice but the idle is so poor I can't get this thing on the highway. The last time I put it in reverse, it stalled when I stopped to change gears.

If it's stalling due to a misfire, you have to address that first. Beyond that, when minimum throttle hasn't been relearned, you'll likely have to drive with two feet and keep one on the accelerator all the time.