how to cure misfire on jaguar xj8?

As mentioned by Nigel, have the diagnostic codes read (OBD Scanners are available on eBay & are a worthwhile investment). You don't mention the vehicle age (could have nikasil lining issues like my xjr!), but coil packs are often suspect too.

Paul Jones (Medical Electronics Engineer - Ex TV/Video/Audio))
September 2009

Hi Richard, have the car serviced and the diagnostic codes read, this will point out if any valve or sensor not covered by normal servicing is faulty/intermittant

nigel
September 2009