engine stall at idle

This is my daughter's '94 Sable 3.8 V6. It stalls at idle but otherwise runs ok. My first instinct is vacuum line but which one? Beyond that perhaps an idle speed sensor or.........?

 

#1)
Pull the codes
(DIY code pull for pre-OBD II EEC-IV controlled engines, which I think this car is: Check here or Here)

Always start there first
Even an "all clear" code tells us something

Then there are a few things
How's the consumables?
Plugs, wires?
Check the air filter, that'd do it right there
As would a old (clogged) fuel filter
Check for vac leaks
There's no one vac hose, it's a close inspection of all of them
Really get in there, especially with the "elbow" lines, they have a tendency to crack
A thin crack underneath an elbow might not be seen or felt until it's twisted or removed, so a quick visual might not find a problem
Might be wise to check the fuel pressure, the TPS, and clean the IAC (Idle Air Control), and MAF sensor, but wait for the code reading before going that far into it

 

Throttle body dirty?.