Thanks for all the help from everyone. I cleaned the air control valve, but it didn't seem to do much good. Then I backed off on the throttle adjustment screw on the driver's side of the throttle body which took the idle back down to where it should be. It runs fine now. We'll see what happens with a cold start in the morning. The local mechanic I talked to thought maybe someone had the adjustment screw on the throttle up so high to maybe compensate for some other problem, but he didn't know what that might be. I wonder if a really dirty throttle body and interior intake manifold would have caused someone to adjust that screw so much? Rethinking my test drive with the car before I bought it, the idle was closer to normal then, which was before I cleaned all the intake parts thoroughly. Thanks again. I learned a lot with the help of everyone.
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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock; 86 240, 129K, once in Rolling, now smashed quarter panel thanks to driver of an F150. Daughter safe in her Volvo.

The Constant Idle Speed circuit, if that is what you're referring to, was used begining in '81. Your car should have it.
I'm a broken record on this but you should set the idle spec by running the procedures described here:

http://www.brickboard.com/RWD/index.htm?id=545436

In your case, don't skip the first two steps.
You can fiddle around with just the idle but if you don't have the emissions controls in proper order and your CO properly adjusted the car will not run quite right, waste fuel and pollute more.
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'80 DL 2-door

Your 81 has K-jet injection. Fast idle can be caused by a vacuum leak anywhere on the intake system. If you suspect the idle air valve, simply pinch it's hose shut with a clamp and see if the idle slows down. It's the gizmo sitting top center of the engine with the big hose in and out.

Idle adjustment is really simple on non CIS kjet. There will either be a bypass hose around the throttle with an adjustment valve in the hose, the adjustment valve may be on the throttle body, or you just adjust the stop screw on the throttle. I am not sure what type 81 kjets had.
Before you do this you should check to see that your air idle valve is working. This valve opens when the engine is cold, increasing the idle untill the engine warms up. This should close within 5 minutes when the engine is started. I would guess that this valve is seized on your car.