1998 Chevrolet C3500 diesel engine dies randomly when driving down the road - uphill, downhill or flat surfaces. Typically doesn't happen when it's cold. Sometimes it starts back up and sometimes it doesn't. When the engine dies, the Security,brake,anti-lock and service engine lights all come on. Sometimes you hear a clicking under the dash. A new ignition switch was just installed and diagnostics done with no answers. The remote mount PMD kit has also been changed out twice as well as the electrical fuel box. All repairs were done in 2012. I am at a total loss of what could be wrong...