I have been chasing the PO193 code for 4 years and at least $10,000.00

My direct precise question is related to the photo attached.

If you bring the 2007 XKR up to about 100 mph, let off accelerator pedal and let it coast down to say 50 mph it will pop the PO193 code everytime.
On the coast down from 100mph the fuel pressure continues to rise(see photo) until it reaches the absolute high of 78.3 and will hold there until auto down shift or if you feather the throttle. The problem is when it holds at that 78.3 psi it pops the Check Engine light code po193.

Does anyone else's car ever do this this?( or what does everyone else's car hold at on coast down ) I thought it should reach max 70 and open the purge valve to release pressure.

Everything pertaining to fuel pressure has been replaced with genuine Jaguar parts.( when I say everything, I mean everything ( the List is very long )

Any Ideas what would cause this fuel pressure to hold so high until po193 triggers

 

You've posted in the wrong forum. This forum is for the Jaguar XK sports cars built and sold between 1948 and 1960, (XK120, XK140, & XK150). Jaguar resurrected the XK designation decades later. It's not clear if you have the steel XK, or the later aluminium XK. There is a forum for each model

https://www.jaguarforums.com/forum/xk8-xkr-x100-17/
and
https://www.jaguarforums.com/forum/xk-xkr-x150-33/