Throttle Position using OBD2

[Buzz]

Hi all, is anyone familiar with using an OBD2 module and the Torque App on a 2.0 Diesel Cruze ?
I bought one of these modules recently to reset the fault codes and monitor performance as the car will intermittently go into limp mode (code 84) while driving along. Typically it will happen while coasting to a stop. I reset it and all is fine again for the short term.
When stopped and at idle, monitoring the Throttle Graph (showing in percentage) on the Torque App, it is showing an unusually high and fluctuating throttle position even during idle at 800 rpm. I would of thought the graph would be sitting flat around 10% but it's more like 50% and fluctuating. If the accelerator is pressed just a little, the graph spikes to 98% and then resumes fluctuating around 50%. This carries on for about 2 minutes then the idle increases to 900 rpm on its own and the thermo fans come on...
This issue is driving me nuts!!!
I have cleaned the throttle body even though there was very little soot, cleaned and checked the Mass Airflow Sensor (MAF), disconnected & reconnected the battery, Engine Control Module and the Accelerator Pedal Position connector.
The air filter and fuel filter have also been replaced with a genuine products.
The most obvious answer would be the throttle position sensor however it is stupidly molded into the throttle body itself and Holden quoted $690. This is an expensive fault finding exercise and hope I don't have to go down this path.

If anyone can shed some light with their experience using the OBD2 and any thoughts on what is going on, it would be very much appreciated.

I have a video but can't post it so have attached a few snap shots.