the engine stutters and then shuts off

Hello, I'd see your local Toyota dealership for a possible in-warranty repair. I'd look at fuel delivery or air intake -- too hard to know without hands on testing -- but especially in California there are extended coverages on multiple vehicle components. Such a new Toyota -- I'm a bit surprised as to the concern occurring. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops