My 6.5LTD Silverado will not start

Did you check the fuel pump relay ? The relay gets power from a fuse and also from the PCM relay. The computer grounds the relay to turn it on for 3 seconds when you turn the key on, then only after the computer "sees" RPM or oil pressure.

You probably should perform a fuel pressure test to see if the fuel pressure is bleeding off of the fuel rails when the engine is shut off. If it is, you could have a bad fuel pressure regulator or a bad check valve in the fuel pump module (which will require replacement of the module).

One way to test for this condition without any tools is like this:
cycle the key ON, wait about two seconds, then OFF, wait about 2 more seconds, and back ON again. Repeat his 3 or 4 times before turning the key to the CRANK position. If the engine starts immediately every time you do this, then the hard starting is definately caused by the fuel pressure bleeding off.

The power stage module,can do this on you vehicle after a hot restart

i don't know that this will be your solution, but i would check where the battery negative attaches to the engine, and check to see if engine to chassis grounds are sound.

you are getting air in the fuel sys. pump on top of filter push it several times until it gets a little resistance . then try to crank it may take a few seconds . it happens after hard driving or sitting for a while.

Sounds like the fuel pump is bad

I'd use a gage and check proper fuel pressure, key on engine off, 60--66 psi with spider fuel system.
Engine cranking did you visually check for spark at the spark plugs? Engine cranking is there a fuel injector pulse?https://s8.postimg.org/50arofh11/fuel_pump.jpg
Click on the link for fuel pump relay, you can check the fuse. At the fuel pump, gray wire is voltage, black is ground.

i would really change the fuel filter, spark plugs and that should do it

take an ohm meter reading on your spark plug outputs between the three coils (if this has that type) big difference replace it and maybe the controller also.

Most probably ur crank position sensor or the pick-up coil is defective (or nearly). What that does is the computer knows where the No.1 cylinder is so that he knows when to send the spark to the correct spark plug. Now ur computer doesn't seem to know where the No.1 cylinder is, so he fires at random. Eventually the spark lands at the right place at the right time, hence ur engine is long to start.
That is my best guess.