After completing 100,000 mile service which included new plugs, car ran well for about a month. Slowly deteriorated but no codes. Got in one morning and no start. Just cranked and occasionally a sputter. Long story short....The new Bosch plugs totally fouled up. Installed NGK's and all has been well. After finally nailing down the Bosch Rep, he admitted Bosch is having a problem with their plugs. It seems to effect the XJ and XK models the most. Local Nascar Racer also had problems with the Bosch plugs. He was the one that found the problem for me.

Peter

 

Great, thanks for following up!

 

Good tips, thanks for posting