I have a 97 chevy 1500 4wd. The other night while I was driving the truck suddenly lost all power. I thought maybe it was the alternator but I had it tested and it was fine. I eventually found that the ecm-b fuse was blown. I replaced it and the truck fired right up. I drove it for about ten minutes and it lost all power again. I checked the fuse but it hadn't blown. The truck still won't start. It will crank good but won't fire. It also seems to run the battery voltage from about 14 when I first start cranking to about 9 when it's been cranking for just a couple of seconds, even when I try to jump it. Anybody have any ideas?