84 Suburban won't idle when warm

[ryno352]

My friend has an 84 Suburban that I may be buying soon. It is a 350 automatic. It fires right up and runs perfectly smooth, has plenty of power, and sounds like there is nothing wrong with it. But after driving it around for a while, whenever it returns to low RPM sppeds or idle, it dies--no sputtering or anything, it just quits. Does anyone know what the cause and solution to this problem might be? Would it be an induction or an electrical problem?
My understanding is that Suburbans of this year are not carburated. I'm historically a Ford guy, so I don't know the exact progression from carburator to modern fuel injection in GMs...is this TBI yet, or does that come later? How hard are these things to adjust? Any help would be much appreciated. Thanks.