Q: I think my motor is toast.

I was driving at about 50 mph when I heard a loud thud from the engine. I suddenly began to lose power (revved to about 4 or 5 grand to stay at 50. When I pulled over it sputtered and died. When I started it again it squeaked and rattled a lot. I think a cylinder is missing pretty bad or maybe it's a rod knock or a screwed up valve I'm just not sure.

My car has 139000 miles.
My car has an automatic transmission.