Good Day

I'm new here and I need some help. I bought a 1997 Galant wich apparently was in good condition. A couple of hours later the car started overheating and after it turned off in the middle of the road it wouldnt start. Now the car wont start unless I have the gas pedal press and after it starts, it will turn off the second I let go of the gas pedal. I know the owner and I used to live with him for the last 6 months. The car has never given them any problems, so it seems it just now decided to do this. Any help will be greatly appreciated.