My gas petal suddenly stopped working

Today I was traveling up hill when my
gas petal suddenly stopped pressing
as if I had ran out of gas ( my tank
being half full). My car then begin to
roll backwards down the hill until
stopping at the bottom. I
immediately turned my caution lights
on, and then turned my car off. Being
in an unsafe place in the intersection
I try to re-crank my car to put it into
neutral, when I did this my engine
begin to run perfectly and I'll begin to
be able to drive again. About two
hours later the same thing happened
in a fast food drive-through. My car
also has been experiencing a delay
in gear shifts, a delay in windows
rolling down, and also dashboard
lights not working.Please respond
quickly if you know what is going on,
thank you.