What have you done so far? Have you checked the brake fluid level?
On a Saxo, the handbrake can sometimes come loose and needs to be tightened. To do so, first turn the engine on and place your foot on the brake. Push in the handbrake button and then pull up on the handbrake until tension is felt. Repeat as needed.
Try reaching underneth to gently tap the fuel pump with a stick.
Timing belt
dirty fuel filter
Yes.
Engine cuts out intermittently, runs rough.
The engine usually gets louder? Shift+/
Lack of fuel it needs to operate
unburnt fuel
Manuel transmission? You need a new clutch.
It is very likely you have something wrong with your engine.
Have you checked the handbrake or the engine temp.