Some while back, I bought a 1997 Audi A8 Quattro with a bunch of problems for a little too much money, let's just not talk about how much. Not a lot, but still too much. I've worked through most of them problems, but then had an electrical issue that sent me back to looking for a front-end harness. Long story short, I wound up buying a parts car for $300 and then driving it home in limp mode over the Hopland Grade, like a boss. And since it's nicer than my car, I'm just going ahead and swapping the long-ago-warranty-replaced transmission which I've had fitted with the Transgo main pressure valve fix into the newer, nicer, lower-mileage car. And yesterday, I actually managed to extract the motor and trans from the 1997.
A stitched-panorama shot of the underhood area.
The Throttle Position Sensor (or "TPS") is an integral part of any electronically-controlled fuel system, even many carbureted systems. It is usually attached to one side of the butterfly valve which admits air into the intake manifold, while the throttle linkage is attached to the other. In carbureted systems, the throttle linkage may also have other functions; in fuel injected systems, it is the throttle position sensor which instructs the car as to how much fuel you are attempting to burn.
This is a Delphi Throttle Position Sensor that I purchased from autopartswarehouse.com.