Engine stalls or is starved when low in gas

Sounds like the pickup tube in the tank has a pinhole or crack. When the fuel is over the hole it is not a big problem, as soon as it goes below it the pump starts pulling air and the carburetor runs out what is in the bowl and the engine stalls.
Replacing it should take care of the issue. Not sure if you will find a new one but if should not be difficult to make a replacement if required.

Thanks Steve W.
I will look into the pickup tube, I did a quick search and you are correct, could not find a Chevrolet LUV specific pickup tube, but could probably use a universal PT and just make some mods? Or is it easier to just build one from scratch? Does not seem to daunting of a task, getting to the tank is probably the hardest part. Looks like a little screen on the end of the PT as well?

I would drop the tank. Remove the tube/sender, clean out the tank and make a new tube out of some steel tubing (like brake line) and solder/braze it to the original plate. You could make it out of stainless as well but it's a bit harder to work with. Most of them use a fuel sock on the end of the tube to keep rust/dirt out of the system.