Thanks BC_Dan, I will try to test or get this tested and let you know what I find. I am a person that likes to know how things work and what they do, so I am still wanting more info on the TPS and how it functions with the motor.
XC, it didn't look like you had your question answered to your satisfaction. The TPS is simply a potentiometer (or variable resistor). It's exactly the same concept as a dimmer switch on your living room lights: as you move the dimmer more open, the lights brighten, and as you close it, the lights dim, all in a very smooth, linear way.
Functionally, there are three wires connected: a ground, a source of 5vdc, and an output. The 5vdc is connected to a wound coil, the output is connected to a sweep arm. As the sweep arm moves from one end of the wound coil to the other, the resistance lowers, and consequently (Ohm's law) the voltage rises. The sweep arm is connected to the throttle body and the throttle, so as you open the throttle the sweep arm moves.
To test, you would connect an analog meter to the output (and ground), supply 5vdc to the source line, and slowly open the throttle. The voltage should very slowly and steadily rise as you open the throttle. If you stop mid-open, the needle on the meter will hold at the same voltage.
Over time, things can cause the wound coil to become contaminated, and when the sweep arm starts encountering contaminated locations that it loses contact on, the voltage will drop. You see this on the analog meter very easily, as quick drops of the needle. Digital meters do not show this very well, it's best to use an analog meter when looking for something like this.
The EFI computer reads the TPS output, along with a bunch of other sensors, to determine how much fuel to spray into the throttle bodies. These contaminated spots on the TPS can cause the EFI computer to overreact, causing very extreme drivability issues and dangerous behaviors of the engine, from a rapid drop to a rapid increase in engine speed. A bad TPS should be diagnosed and replaced ASAP.
Actually, here's a really good article about the TPS. It's really meant for a car, but all TPS work the same. You can actually skip what I have already written if you like, I'm leaving it here because I took the time to write it and am not about to throw it all away.
Symptoms of a Bad Throttle Position Sensor | eHow
Hope this helps!
Alex