why does it matter if you're driving down a hill? At least it didn't cut off when you were driving up a hill? And I don't know why it would cut off I'm 13.
IF it is Turbo charged then that would be the turbo.
get an engine diagnostic scan.
There are 2 fans that would be running while you are driving and that is normal... the compressor fan if you have the air conditioner running and the radiator fan runs to help keep the radiator cool while the engine is on.
On a 1994 Buick LaSabre why does the engine continue to rev up while driving even when the brake is applied ? or when driving why doesn't the engine return to idle when the brake is applied? I would check for a vacuum leak
blown engine, out of gas janitorial duties.
It might be a broken motor mount or transmission mount.
your Alternator
air leek
Check to see if you are getting fuel and spark
The year, make, model and engine info would help.
My 1999 Pontiac Montana would seem to "skip a beat" while driving. It then started stalling and restarting, all while driving at highway speeds. My mechanic found that an electrical cable that carried an engine sensor signal was leaning against a hot part of the engine. The cable insulation had melted or worn through, causing intermittent shorts. The shorts confused the engine computer, which then stalled the engine. He simply rerouted the cable and all was fine after that.
Had to disconnet my radio it was shorting out the engine.