I recently bought a C43 Amg. I love the car but it has a problem starting every once in a while. This has become a huge inconvenience. I tested the starter and battery. The car turns over but gets no gas or spark. The problem is intermittent so the shop I take it to can't find it. They say, "It starts for us." It's really pissing me off. Any suggestions on what the problem is and a good bay area shop that will help find it at any cost? I don't know where to start and am discouraged to drive the car for fear of it failing.