I recently bought a 1996 XJ6 with 90,000 on it. The car runs great most of the time. Won't pass inspection due to random multiple misfire in bank B. All the O2 censors were replced, the exaust was repaired and gone thru. I have spent a ton of money and need a more specific place to start. My mechanic seems to be eliminating things but at a high cost. No engine light has ever come on and we know it works. It comes on when you turn the car on. The car will drive fine, then loose power and idle rough. The faster you go the less it happens. It also seems to happen up hill more. Can you please help I love this vehicle and want to keep it to give to my son.