6.0L LQ4 Fuel injection

[bowtie_nut]

Okay fuel injection guys I have a question. I have a 99 silverado with a 6.0L factory engine. It has problems starting. The engine sounds like it is starting so I let off the ignition and it dies. Some times it will start and run fine, then I shut it off and try it again and it won't start. The check engine light never comes on at any time. I have checked the fuel regulator on the fuel rail and cleaned around the throttle body with carb cleaner. Does anyone have any ideas?