Watfordx5

I'm taking the car elsewhere for a second opinion as the guy was a bit of a clown. Will the fact that he cleared the problems effect the next person who looks at it? Expensive fix? Thanks for the help

Hi all I'm new to the site, had my 04 bmw x5 4.4 v8 about 3weeks now. After a week of owning the car my engine light came on for a few days then went off. This morning about 30 seconds into my journey the light flickered and came back on along with the car juddering. It was like driving on cobbles and had a loss of power. I drove to a garage where he said it was misfiring and after a diagnostics check he revealed it said ALL 8 CYLINDERS were misfiring. He was a bit baffled so cleared it incase it was from previous work that had been fixed but not cleared. He then started it up again this time it only showed only cylinders 1 and 4 were misfiring, any ideas why anyone? Im not the greatest with cars engine wise. Could it be the coil packs? Or more serious? Help would be great as I don't want to get ripped off so wanna be clued up. Thanks