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I had exactly this issue on my '87NA - with the culprit being a poorly functioning ICV (Idle Control Valve), which I believe is similar to the ISV (Idle Stabilizing Valve) on your '83.
On my car this is basically a stepper motor which works both electrically and in conjunction with the pull of negative (vacuum) pressure from the intake manifold to which the ICV/ISV is attached, via. a vacuum hose.
I can test the ICV on my car by disconnecting its electrical lead and jumping the two outer contacts (there are three total) to a 9 volt battery and listening carefully to ascertain that the rotor within flicks back and forth, otherwise the ICV itself might be the issue...and if so it is possible to remove it, bend some tabs to pop its cover (don't lose the O-ring!) pull the rotor/stator assembly out and clean this up, also possibly bending the three brushes inwards to refresh contact with the inner rotor.
Reassembly can be a bit frustrating as you will be working against some pretty strong magnets within the assembly to get things back together. Don't forget to reinstall that O-ring (check it first for cracks) as this is needed to hold vacuum, and re-bend the metal tabs and you're good to go.
But if the ICV does pass the 9 volt battery test, the problem likely lies in the "S" shaped vacuum hose, either in its connections or, more likely, that it has developed cracks...which is actually pretty common as the whole assembly is located more or less out of sight underneath the intake manifold, which also makes it a bit tricky to either service in place or remove - without removing the intake manifold first.
Such a check and removal of this valve with the intake manifold in place is possible with the aid of a long screwdriver or hose clamp removal tool, a good flashlight, and a well rounded vocabulary of colorful language.
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