I exhausted every avenue and replaced several good parts before I found this. I had transmission mode selector lights that would start flashing as soon as the key was turned on. Also the up shift arrow on the dash would flash on & off as well. I finally got it to fail with no spark on 2 adjacent cylinders at the same time. Since the ignition control modules for the even & odd cylinders are seperated that eliminated that possibility. The only thing those have in common are the ECM & a ground connection at the left motor mount just above the steering rack. I had checked continuity previously from the bolt to ground and gotten a good reading. This time I removed the bolt and connected both ground wires to a common ground back to the battery negative terminal. As soon as I turned the key and the transmission mode lights didn't flash I knew I was on to something. The 2.9 sprang to life on 4 cyl, the 2 plugs were still removed and were firing like crazy. This is the ground Volvo identifies in their schematic as a "power ground". I'm not sure of the terminology, but I found out if it just sputters and dies and won't restart, look here before buying any parts. These are the individual grounds for the ignition control modules. FWIW. Hope this helps somebody.