Hello mate,
so litrly had the same problem a month ago, and it's the manifold not an easy fix, I had numerous diagnostics and in the end I spent £145 on a diagnostic from jaguar to determine the issue when the looked at it, it was the offside manifold.
part was £435 (all new manifold and pipes)
futting and service £1000
i can send all details via email as I have kept all documents.....
i reccomend take it straight to jag for the diagnostic, ask them when finished to print off what is called rag sheet ( all faults numbered ect and faults) and go from there...
dont hesitate to message me
kind regards
Dave