2001 grand marquis turns off at idle
 

I have a 2001 grand marquis.

Recently, she turned off twice at idle.
The first time, after I passed a bump with low speed, she turned off. But I can start her right away. And she had no problem turning on again.

The second time, when I was gonna back, after "R" was set, the same problem happened.

btw, there is another problem. after I turn the ignition on, I can hear hum noise from the hood for about 30 sec.

Any advice about the problem?

thank you very much!