If the sensor had an electrical fault it should have shown up in the diagnostic test, what it sounds like is that the ECU does not know what position the throttle is in,
To check if it is sticking you need to feel with your finger that the throttle pin below the throttle arm lever is up against the sensor contact lever, then open the throttle fully & then release it, then again check the contact lever has returned.
Other option would be to remove the two screws holding the tps, but the back one is really difficult to undo.