2003 Kia Sedona fuel

You need a better diagnosis than, "they thought, ..." The first thing, once you get it to stall again, is to check for spark. Also check the diagnostic fault codes. If spark is missing, the most likely suspect is the circuit that triggers the Engine Computer to know when to fire injectors and ignition coils, AND turn on the fuel pump. This is where a lot of people get derailed when they see low fuel pressure.

You'll need a code reader to get the fault codes out of the Engine Computer. The people at many auto parts stores will do that for you for free.