<<< the only thing that jumped out was the throttle position shown as either Idle, partial load or full load was dropping down to invalid, which shows the car going flat. However other parameter's seem health, such as throttle position in volts, acceleration in volts and relative data >>>

Aside form being the fault, this could be a scan tool glitch or a software error in the ECU. Can you link the invalid pid to the symptom occurring as regards timing?

I am not familiar with the system and didn’t look it up but the idle, part and full load could refer to a load signal which is calculated rather than measured. In other words a fault elsewhere, eg maf or map, could cause this. Were there no fault codes?
I think if you post the data, captured when the symptom occurred, it might help.


<<< I don't know how to post my data on ukat. >>>

If you email it to me I will post it for you.