I have a 2001 Z71 with a 5.3 liter. When I first turn the key it turns over but doesn't start...even if I hold it on the initial attempt for a while, it still won't start. But if I let up and then turn the key again, it usually fires right up like it should. It's almost like I have to give the engine a wakeup call and then it's fine. Does anyone have an idea about what this might be? I was thinking it could be the fuel regulator from reading other posts, but nobody seemed to have startup problems quite like this.