Hello, guys. I am trying to find the part numbers of the spark plugs, coil on plugs and their leads. For the moment i have found for the spark plugs - NCA3850HA2 and for the coil on plugs - XR827823. I couldn't find the coil on plugs wiring as a part number if there is any and the part number of the distributor cap. I've got the car for an year and the engine was running smoothly, but it started to make some problems recently. I would like to change all wirings, spark plugs, etc. for a start. Any help will be highly appretiated

 

The engine does not use wires from a distributor cap and there is no distributor cap. The wires connected to the individual coils are all part of the main engine wiring harness. The coils get all of the information for firing from the ECM Engine Control Management Module.
Unless you have broken connectors, broken wires or have had an engine fire it is unlikely you need to replace the wires. Throwing parts at a Jaguar is a very expensive way to resolve problems.
You would be better off to get the OBD codes read and post them here and we can help you figure out why the change in performance. While getting the codes read you need to check short term and long term fuel trims ( stft/ltft) and post them.