Help. My a class developed a misfire and hesitation about two weeks ago. After abit of research a common known fault is the throttle body. Ive had that cleaned out and the sparkplugs checked. when I drove home from having this done initially the fault was still there but after a few miles it run perfectly. I stopped at the shop and when I started up again the fault had returned. Ive got not warning lights up on dash. Any ideas??