Restricted performance light on a jaguar xjr 2005?

SOURCE: 2001 Jaguar XJ8 Idles rough while sitting

o2 sensors often cause a rough idle at stand still. Previously my xj8 had crank case ventilation (pvc valve essentially) issues that caused the check engine w/ restricted performance. I noticed a severe drop in gas mileage as well. Jaguar dealer fixed my problems in a few hours and it was surprisingly cheap. Its worth taking it to advanced or auto zone to see what the computer says. Then decide if you want to shell out for a dealer fix or if you can tackle it yourself. BTW, just to justify myself this is my third jaguar. I have a '94 xj6 with a chevy 350 inside it, previously owned a 95 XJ6 and currently have the xj8. They are wonderful cars if you can put up with their rough times.

SOURCE: Jaguar s-type restricted performance displayed

Its most likely the coils and spark plugs, sometimes caused by oil leaking from the valve cover gasket. The coils deteriorate over time from engine heat and need to be replaced at 90-100k
Local garages don't have the Jaguar diagnostics terminal and are unable to do more than find basic error codes with a reader. Its important to get this fixed because it's causing damage to your caltalytic converters. They are expensive.

SOURCE: Engine Light on and Restricted performance message

Replace the mass air flow meter.

SOURCE: 2003 Jaguar S Type R 4.2L SC. Check engine light

Rent a scanner, read out any code(s), and pursue to repairs. It may be as simple as bad spark plugs and wiring, or worse, fuel problems from the injectors back to the fuel tank. A worn O2 sensor can cause improper fuel/air problems.

SOURCE: jaguar s-type restricted performance

I had the same problem. Restricted performance and running rough at 3000 RPM. I have an OBDII code reader and found that the problem was in the air mass flow sensor, which is just after the air filter. I pulled this out and found it was dirty and had butterfly wings in it. The last shop where I had the oil changed replaced the filter for me but put in the wrong size. Close but no cigar. Bought some *** Flow Sensor cleaner at auto store and fixed the problem. Get an OBDII reader with the ability to erase the codes. Comes in real handy.