Engine Failure problems of the 1997 GMC Sierra

I purchased this truck new, and at approximately 23,000 I was driving the vehicle at around 55mph when the engine failed. It did not sputter or knock, it just quit, all the gauges, engine quit instantly. I pulled over to the side of the road and turned the key off, and then re-started the engine. Motor started without hesitation, and I proceeded down the road. Two days later, with lots of driving time in between, the same thing happened. It died, I pulled over, turned of ignition, and re-started the motor, and again the motor started without hesitation. About two weeks later, I was driving at about the same speed and again the same thing, except this time the motor would not re-start. Vehicle was towed to the dealership, and it was determined that the fuel pump had failed. It was replaced and I had no problems until about a month ago, approximatley 05/15/2001, my vehicle started to behave in the same way. While turning left at an intersection, the vehicle died, and I was in the middle of oncoming traffice that was approaching. I re-started the engine and proceeded to get out of the way of oncoming traffic. This has occured several times over the past two months, with the most recent event occuring yesterday, 07222001, in which I was almost "t-boned" at an intersection when the engine failed. I have kept the fuel filter changed and I not use the same gas station consitantly. The fuel pump has always made a loud buzzing noise, even the first pump that was replaced at the dealership made this same noise. I understand that GMC re-designed this pump for this 1997 model. What realy got me interested in this problem, is not only the fact that I have had some close calls with almost being involved in an accident, but one of my CO-workers is having the same apparant problem with her "1997 GMC jimmy. " it has the same vortec v6 engine as my truck. The delearshipt stated they can not id the problem, unless it "runs a code, or fails while they have it. Thanks.