this is a quick recap of events on a low mileage Jaguar.
1. got the car and it had a rough idle
2. random misfires on ALL cylinders
3. bad oil not changed in a while
4. Bad Catalytic converter
5. Engine timing was off had to pull engine and reset timing and replace VVTs
Root Cause - bad engine performance Tune
Something no one ever suspects when getting a older 2006 to 2009 XKR is someone tried to have it tuned by someone that is not a Jaguar trained tuner.
Found this out after I got the engine running and no Codes, but some of the data points were incorrect.
then the manual says engine can not rev over ~4000 RMP in park and this one did, also the transmission shifting was odd.

Bottom line - I found a Jaguar tuner in California for an unrelated item and discovered the safety tables was removed or altered to allow the car to perform unrestricted or so they thought this is bad.
the tools used are for awareness only this is not an endorsement or anything just providing because these are the tools the tuner guy used to figure out my Jaguar.

Examples - there are other sources just referencing for awareness.
https://tools4car.co.uk/product/jlrcable/
https://www.obdii365.com/wholesale/k...-firmware.html