Engine would spontaneously die/kill at various speeds, and would have no power steering, no power brakes, and even no headlights. The dashboard would then display "reduced engine power" and "starting disabled". After waiting 30 seconds to 2 minutes, it would restart and get us home. However, the issue methodically began to occur more and more frequently over the following months. From once every couple weeks or so, to then killing several times driving across town, and then eventually killing after only one or two seconds of being started, finally to not turning over at all (with no dashboard messages...the dashboard went, and stayed, dark).

RESOLUTION: the dealer identified a short in the wiring beneath the fusebox in the engine area. The short was causing variable voltage from 8 to 12 volts to the Engine Control Module/Unit aka CPU, zapping the ECM/ECU into a sudden shutdown. After a grand total of 2 to 3 dozen zaps/shutdowns, the ECM apparently was permanently fried. By identifying and fixing the short in the electrical wiring (less than an inch long of wiring was replaced), then by installing and reprogramming a remanufactured ECM, this serious issue was finally resolved. After such a long journey, I'm thankful to the Buick dealership and their mechanics as quite a few vehicles with this kind of difficult problem probably never made it back on the road.