The throttle position sensor is an important part on your vehicle to keep it running smooth.
The throttle position sensor as the name suggests senses the position of the throttle and the throttle position sensor is usually located on the butterfly spindle/shaft so that it can directly monitor the position of the vehicles throttle.
It lets the computer know how much or how little fuel your vehicle needs depending on how wide open or how closed off the throttle butterfly is in the throttle body.
If your vehicle is running rough or having idling problems then it's a good idea to check the throttle position sensor.