Car Stalling/Shutting Off

[The1One1AndOnly]

Around a weak ago the car started turning off at lower speeds randomly, then it picked up and would turn off constantly, Now it even turns off at high speeds, I was doing 60mph on the FDR in NYC, and the car just shut down! I had to wait to a full stop and restart it. The car restarts right away. But after one episode and keeps shutting off over and over. Sometimes I can drive for half a day and it fine, then all of a sudden it stalls and shuts down. Once that happens it begins to repeat. I had a mechanic check it with the old computer, and said that it was the CRANK SENSOR that was causing this problem. The interesting this is that when I keep guessing it will continue to drive, so I guessed that maybe there is a fuel pump issue. I don't know.

I would be extremely grateful on some feedback, and see what you guys have to say, since you specialize in this. If it is a crank sensor, is the crank sensor expensive new? And is it worth buying it here used?

Thanks
Max