Engine stalls and will not restart until after a hour or two.

I would start by checking the fuel pressure at the Schrader valve on the fuel rail. It should be 56 to 63lbs. When doing so, once fuel pressure is built up, let it sit for 3 minutes. Fuel pressure should not drop more than 5 lbs. If it bleeds down then there would be a leak somewhere like a fuel injector, the fuel regulator, or even the fuel pump.

Did you found the problem im having the same problem on mine

We're having the same problem with our 2018 Tahoe. Had it stall out 3 difrent times now , in a few dangerous situations. Must be a recall issue. We have taken it into the dealer and they can not find the problem and said it has to be doing it for them to know. The light comes on and the Onstar diagnostics says, "The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs. Service within 1 day