Sorry you have invested so much.
Both fuel pump and ignition module/coilpack have a history of failing under specific temperature condiditons.
Never let the car run out of fuel. It will burn out the pump.
Try the coil pack first or should I say next.. usually can find one at a JY.
Pick up the Ignition module at the same time if you can.
The ignition module sits directly under the coil pack is next and a little more difficult to get out.
It is a bit more suspect since you said your Crankshaft sensor seemed to help for a while.
I agree on the comfort and own 3 Buicks now just because of it.
Of course its best to try to determine if your not getting fuel or ignition but the ignition module addresses both.
If you want to troubleshoot it just carry a bottle of cold water and drive till it quits when hot and pour the cold water over the coil pack and ignition module combination. Try and start it and if it fires up or fires much better, its highly suspect.
Just to know if the Crankshaft sensor was bad it would not try to start or sputter until it worked well again the coil packs will. The Crankshaft sensor stops the engine completely. Its usually quit or working. OFF or ON. The engine will not usually sputter or try to fire.
Good Luck