1995 disco 3.9 v8 automatic trans, 125000 miles. Been doing this for last 5k or so. I tolerated it till now, but my kids are getting old enough to drive it and I fear that their lack of experience driving and this may cause a panic or get them in trouble.

After getting up to temp while driving, vehicle will shut down when I come to a stop, idle. It always restarts easy and drives easily to next light but will probably shut off at next light. Seems to idle rich after coming down from higher RPMs, seems to.
In the last 250 miles I have replaced both O2 sensors, I believe this model year has only the two. After it ran good for a day or two then went back to its evil ways.
Noticed an exhaust leak and loose bolts on exhaust manifold. This was an adventure as I replaced the manifold bolts with studs and had to helicoil two of those studs in. But it runs quiet now and ran for three or four days with no idle stops... and then it has done it again occasionally these last few days.

The disco runs great otherwise and never throws any codes.

Seemingly unrelated, in this 5k miles I recored the radiator and replaced the fan clutch. but it was doing this before I did that work.
Also I live at a very high altitude. 8700' and drive between 6000' and 10000' all the time. I work at 10300' altitude.

I'm going to look at things like the throttle position and map sensor this weekend as well as make sure that my vacuum lines are in the right places.

 

while you're at it, check /clean the idle air control valve......just clean it and the hole it fits into..dont try to adjust or move the plunger, Also clean the throttle body and butterfly all those can affect the idle speed