My 2004 XJR has a flat spot from rest that is really bugging me, lis not there when I have the sport button pressed but I don't want to run in sport all the time. I have tried a hard set but no change. Anyone have any ideas.

 

Mine did that when the tires got old and uneven. New tires fixed it. It also did it on a tank of bad gas, when the motor kept surging, but that one also threw a lean code...