[V]

i still say alt, died while driving gives an idea that alt went at some point car continued to run on batt power only till it couldnt sustain it anymore, probably brakes lights or such. when shut off batt recouped enough to just crank it one more time since engine was hot and fired right up, but with no more juice left, it died again.

so i say alt

try jumping the car. it should start but as soon as you remove the jumper cables within 1-2 seconds it'll die.