I have a couple of intermediate problems on my 2004 xk8 convertible. Check engine light comes on for a few days then goes off for a period of time. Restricted performance comes on for a short period of time and then goes off. Head lights flicker most all the time , and dash lights and headlight will not come on at the same time. Either one or the other. There is a whining noise coming from the rear end. The yoke on the rear end was replaced about 3 months ago. Help would be appreciated.