Error codes cylinders 2 and 6 misfiring and flashing engine malfunction and Cruise not available

I had a continuous engine malfunction light. The code said B bank O2 sensor. Changed it, still got the same code. THEN, while driving, the cruise not available indicator and the engine light started flashing for a few seconds and went off. I decided to have the spark plugs changed. My mechanic changed the spark plugs and noticed the valve cover gaskets were leaking and there was oil on one of the coils. He replaced the gasket(s) and the two coils. The car ran well for an hour then the flashing "cruise not available", and amber engine malfunction flashed for a few seconds and stopped. It happened a few times while I drove but didn't stall out. Now I have a steady engine malfunction light
The new codes (he uses a generic code reader, not specific for Jaguar) now reads cyliners 2, 4 and 6 are misfiring. Any suggestions?