Tahoe Starts, Dies wont start anymore

[Beefy350]

Hey guys, Im new to the Forum and while my mom was driving my 95 Tahoe it overheated and shut down. We went to pick it up the next day and it still wouldnt start, it would crank but that was it. A mechanic told us it needed a new engine. We brought it back home and a few days later i tried starting it, and it started. I drove it around for 2 mins and when i shut it down it ddnt want to start back up again.. did that about two times.. has had a new radiator wires/plugs and thermostat installed but still nothing will get it running. Anybody have anythin similar to this happen?
Thanks for the help

 

[SunlitComet]

So can you run it longer to any length of time or does it shut down after a give time or engine temperature? And between the few day after bringing home and turning the key absolutely no one or thing touched the vehicle correct? Those parts were put on after the overheat or before?