I have 3 american cars, my daily driver being a 1984 Chevrolet Camaro Z28 with a 305 cubic inch (5 litre) V8 engine and auto transmission. It has the standard Rochester quadrajet 4bbl carb, but has a manual choke kit fitted (I rarely use choke). On a cpl of rare occasions I have had high revs, once I turned the ignition off and starte the car again and it was ok, another time I drove the car and after a while it cleared itself.
I believe the 1982 caprice has the same 5 litre engine (chevy short block) but I'm not sure if it will be crossfire injection as fited to the camaros in '82.
The wife drives a 1984 Camaro 2.8 litre V6 with auto choke, that revs highish until warm.. pressing on the gas pedal with a quick rev or two can knock the auto choke off and normal idling will resume. Rainagain has provided some good answers.. In addition, it could be the throttle position sensor or a air idle control sensor. If the revs are racing up and down (known as "hunting") it could be your timing is out. I know where to get spares and a good mechanic if you need any help.
Good Luck !!