The TPS is relatively cheap and easy to replace. Try this before you look into more exotic (and expensive) solutions. Although it's possible to replace it while the throttle body is still on the car, I suggest you remove it and take the opportunity to give it a good clean out while it's off the car. Instructions from the Holden Service Manual below:
REMOVE
1. Disconnect battery earth lead.
2. Remove four dome nuts securing the engine dress cover assembly to the inlet manifold studs, lift off and remove the cover assembly.
3. Lift up retaining tang on TP sensor wiring harness connector and pull connector from sensor.
4. Remove the two TP sensor to throttle body attaching screws.
5. Remove sensor from throttle body taking care not to lose the drive adapter
NOTE: The "drive adapter" is a plastic cover that loosely slides over the end of the throttle shaft, on the TP sensor side of the throttle body. It is captured in place when the TP sensor is in position on the throttle body. The drive adapter could fall from the throttle shaft after the TP sensor is removed. Ensure that the drive adapter is not lost.
REINSTALL
1. Check that the drive adapter is in place on the throttle valve shaft, refer to previous NOTE.
2. With throttle valve in the normally closed idle position, install TP sensor on to throttle valve shaft and throttle body at a position 30 degrees clockwise past throttle body attaching screw holes.
3. Rotate TP sensor anti-clockwise on throttle body, and install TP sensor attaching screws and tighten to the correct torque specification (1-1.5 Nm).
4. Reconnect TP sensor wiring harness connector.
5. Reinstall engine dress cover to the inlet manifold, ensuring that stud grommets in the dress cover remain in place. Tighten securing dome nuts to the correct torque specification (4-6 Nm).
6. Reconnect battery earth lead.
