I have a 2000 XJ8 that I have babied since nearly new with 168k now on the Odom. I have an intermittent Restricted Perf that will typically go on and stay on withing a half hour of highway driving. The Rest. Perf. also has major misfiring. My code reader shows P0128 (Coolant, may be unrelated) but more importantly P0356, P0301, P0302, P0303, P0304, and P1316. With readings of Cylinder 1 thru 4 misfires, my guess is that it is the computer for the entire bank. Could it be just a wiring contact since it's intermittent, or a faulty unit? I'm an amateur mechanic, but I have a good set of tools and can figure most of this out, I hope. Pleae advise, and thanks. Happy New Year!

 

P0356 indicates coil fault for #6 cylinder. need to replaced coil and plug first and then test drive car.