Hesitation on 2009 Chevrolet Traverse

2009 Traverse out of the blue started to hesitate to start, did it for a least 3 days. then it will try but couln’t . had it towed to my mechanic when we got there it statrted like there was not problem. used it for a couple days, started to do the same. Took it to the dealer to have the right dionosty done. They said it was the alteranator, had it replaced, it still to hesitate to start, replaced the battery, it start but after a day started to do the same. I had it witrh it. neither the dealer or my mechanic can find the problem. NEED HELP…!!!