Rep Power: 0

Ok so one day I was driving my car from work and it just randomly dies at a light it would start but it would just stall so I had to tow it home. I called my mechanic to come take a look at it and he said fuel was good it had pressure it had spark he told me what he think it’ll be is the key or the ignition switch. I changed the ignition switch earlier and it does the same thing. Anyone know what it could be and can a bad key cause my car to shut off right away?

 
Rep Power: 119

First thought is the timing belt might have been jumping and finally got 3-4 teeth off.

Thats of course under the assumption that without turning the key off, your able to get the engine to restart for another moment with additional cranking.