Sam means well and he probably knows a lot more about cars than I do (which is very little) but.... If the engine turns over then the starter motor must be working.
If it needs lots of throttle to keep it running then that suggests lack of fuel - I'm sure cars have a fliter in the fuel line - and a fuel pump in the tank is the modern trend I believe.
I suspect fuel starvation of some sort.
And Sam's right - you could at least say if it's petrol or diesel - age, engine, condition of battery etc.
Good luck...
Peccavi
February 2010