While pulling a small utility trailer with our 2008 Cadillac escalade we get off the freeway and start slowing down and suddenly, without warning the engine cuts out. When we try starting it again it turns over but doesn't actually start up. Right after it gets towed to the dealership the tech immediately starts the vehicle with no problem. They have been running every possible test on it for the last 2 days and have been unable to find anything wrong. Not a single code comes up. Can anyone help us?