If you have over 60,000 miles on the X it could be your intermediate levers. What happens is when it is misfiring the computer senses the misfires and turn off the injector(s) to prevent gasoline from entering the cylinder and exiting to the cats where unburnt gas will eventually damage the cat. By shutting down the engine and restarting you reset the computer and by that time the eccentric cam has warmed themselves enough to make up the difference in tolerance. Cost to replace the intermediate lever is about 3,000 for new parts and 20 to 30 hours worth of labor. So if the shop charges 100 to 150 per hours you are looking at 2,000 to 4,500 on top of the cost for parts.
Find yourself another dealer. This is a well known problem with the N62 V8.