Kia forte starts but dies instantly. Stays off if i put my foot on gas for a few seconds. Only does this once a day when i first start my car

What is your question?

I have a 2015 kia forte at 45,000 miles. I got it at 42,000 miles. I have had it for 5 months It started doing it maybe a month after i got the car, it only happens for the first time everyday that i start my car (so i guess when its been sitting for 10+ hours) . I turn my key and the rpms go up but then go right down and dies. If i put my foot on my gas for about 5 seconds it stays on n i have no issues after that till it has sat about 10 hours or so again. So the next day. But once my cars on its perfectly fine. It first started doing it maybe 4 times a week and now it turned to everyday. I took it to kia as i have a warranty on it and they told me they saw nothing mechanically wrong with my car and they didnt have an issue getting it on ( they only had my car for 2 hours i told them it only did it after sitting for 10 hours +] . Any ideas what this could be? (The radio stays on if that helps at all)

What makes this problem better or worse?

Does it only first time i start it for my day.

How long has your 2015 Kia Forte had this problem?

3-4 months