Same thing happened to me and it turned out to be my crank sensor.
My car would suddenly die at times and after sitting on the side of the road for a few minutes, it would start back up and run fine. On one occasion it was bucking on and off at about 55 mph. Then one day it died and wouldn't start. I first replaced the ignition switch as the path of least resistance, (didn't help) then the crank sensor which must have been my problem all along as I haven't had any hint of a problem since. I didn't think of the crank sensor at first because of the problem being intermittent, I just thought the crank sensor would be good or bad, but evidently it can be right at that point of working at times and suddenly stop working. I hate it when that happens!
You may try looking at your ignition switch in the column and see if it is loose or coming apart and take it from there.
Hope this helps