I am having a similar problem with my 96 Suburban It runs fine and stalls takes 20-45 minutes before restart is possible have noticed that the Glow Plug lite does not come on when the restart is attempted but it will flash several times when the system allows a restart it is not a PMD as I have replaced them twice during the last 3 months and when the failure does occur the PMD temp are at 60 -70 degrees F and no codes are showing up on the scanner. This problem has occurred when I start the truck in the mornings.Am I looking at a PCM failure or an ignition switch failure