Caprice Michelle Letbetter-Barris

Hi! I've been having issues with my 2016 Journey completely shutting off. The first time it happened was 3 weeks ago I was getting off the freeway I couldn't push down on the brakes and I had no power steering. I managed to get the car stopped, had to restart it and then everything was fine. Took it to the dealership and they couldn't find any codes and told me nothing was wrong. Same thing happened again today when I was coming to a stop. I put the car in gear pushed the button and it restarted. This really scares me since I'm getting ready for a road trip. So far I'm noticing this is only happening when I'm running the air and coming to a stop. The dealership hasn't been able to duplicate. Not sure what to do.