takes 3 cranks to start

I have the exact same problem with the exact same truck and I have done the exact things you have!! I'm figuring it could be the fuel pump itself?? Try turning your ignition on but not starting the truck a couple of times to build pressure. Then start it and see what happens... This could indicate a struggling fuel pump if it starts up after having time to build pressure. Good luck and if you figure it out for sure let me know!!!

The problem is the fuel pump! Chevrolet designed a pump that needs to be cooled by the fuel that is in the tank. If you run the tank too low on fuel, the pump will get hot and eventually the pump will fail. So replace the pump and it will start right up. Just don't let the fuel tank get lower than 1/4 and you'll be fine.