Starting Issue On 07 5.3l

[PaulSC]

Hi, I'm new to the forum and have a question? I own a 07 Silverado Crew Cab 2wd with 13000 miles on it. The last 500 miles or so on the truck I have had an issue with the truck not wanting to start on occassion. I have run E85 and 87 through the truck from different stations in different cities. First time at the dealer I was told they don't know of a fix and drive it. They blamed the fuel. After two weeks of recommended fuel, the truck is still doing the same thing. After getting rude with the service rep and manager they agreed to actually try to fix the truck. They keep the truck for a week and supposedly changed the #5 injector. One day after getting the truck back it started the problem over. I am just wondering if any fellow truck owners are having the same issue and actually have a dealer service department not full of lazy dumbasses. Thanks