Chevyguy2014

Rough idle/cold start code on my 2014 Chev Silverado for the second time now. First issue was at 84,000km. All 8 injectors were replaced under warranty June 2016. Now just over 1 year later and at 123,000km the light is on again so I brought it in and same thing. They said it was all 8 and it's not covered under warranty but maybe GM would do something being as my warranty just ran out at 120,000km and one month after the year warranty on the first 8 injectors being replaced was up. No response from GM and now they are saying only two injectors need replacing. My truck has been at the shop for a week and I'm on the hook for the rental. They say they will cover half the cost on a goodwill plan. My cost is $580.00 plus a week of rental costs. So how long until the next 6 go? What is causing this issue is what I want to know. I only run premium fuel....