How many miles are on it?

 

Just over 300k

 

What happens when it dies? Are there any codes generated? How often does this happen? Did the mechanics say what kind of things they tried to diagnose?

 

Happen every time I drive it no codes just dies. It will crank but not fire. When it dies it literally acts like the key was turned off. The last shop told me I was losing power to all 8 coils at the same time and said it was the PCM so I had a new one installed and still same problem literally no difference.

 

As an active member of the SSR forum, They have what would seem to be a similar problem. It was finally traced to a (broken copper wire within the fuse box)........Kinda a "hair line" crack.
May have nothing to do with your problem, but you might want to open up your fuse box and get inside to where the connecting wires are and look for any suspect break in any of the lines.

 

Maybe try getting the engine running, then shake the wiring harness around the ecm and the injectors.

And perhaps check fuel pressure on the rail, to ensure you are getting fuel.

 

We had the same thing happen on an Olds 3800 v6. It was the crank sensor. Never had any codes.

 

Well,, with the price of used trucks you should at least be able to get your $400 back!

 

I had an 86 Firebird that did much the same. Evidently the fuel pump would get hot enough to only get some pressure to the front, after 3 AC Delco fuel pumps, we finally put a Bosch and never had the problem again. Still just air, fuel and spark, spark is the easiest to check, they usually start but won't run well if it is the others.

 

(I know little compared to some in here), If you have ever had ignition cylinder/key problems, maybe passlock could some how be getting triggered (worn/bumped). It will crank, but it won't fire. The passlock will trigger a security light, and it will reset after 15 minutes.

Other than that, could it be something heating up, and needs time to cool?

Do you notice any similarities for when it does it? If it happens every time it does, is there a certain time frame or anything you notice? Is it after a few minutes, an hour, a certain speed, does it change depending on how hot it is, or how far you go?

Long shot, but if you haven't figured it out after 4 years, here are two things in this video.
Chevy Truck - No Start No Crank - YouTube

 

The one thing that saves me every time is being able to see live data with a scanner. Even when cranking and not running, a scanner will still show whether it has crank signal, fuel pressure, tons of important info.