I finally have narrowed down what is causing the car to surge. It has to be the throttle position sensor located in line with the throttle linkage and connected electrically. When the car starts to surge, a slight rap on the sensor and thinks settle right down to a normal idle.

Anyone know what that rascal is like inside? It is riveted on. Is there any cleaning or repair capable of being done to it? What is replacement like and how expensive or what part would really have to search for?

Thanks much!

The TPS is basically a potentiometer (like a light dimmer switch). You can check the resistance (ohms) to see if it is still good or not. To replace it you'll be replacing the whole throttle body since no autoparts store has a listing for the TPS. You can also take your chances on an Ebay TPS, you'll have to drill out the rivets on your throttle body and replace them with screws when you swap the TPS.