I have a 2000 ford festiva that breaks down if the

Now this is just a guess so please don't be upset at me if it does not work but it sounds like there might be possible excess pressure building up in the gas tank causing something similar to vapor lock in a non-fuel injected motor. I do not know if this will work due to your car is fuel injected but if it has been sitting in the sun all day try loosening the gas cap and release the pressure in the tank then try and start it. I remember a car one time that had a problem like this. The vapor canister for the fuel tank is supposed to release excess pressure in the tank. If the car is sitting in the sun there will be more pressure in the tank due to air expansion. The less gas in the tank the more pressure.

does it run for a bit then die if so its normally the heat sheils from the manifold has fell off or been removed and it causes the fuel to emulsify or just get to hot and the manifold gets to hot and the exhaust heat shield missing... also check the breather from the fuel tank is not blocked and causing to much preasure in the fuel tank
. if it dies try open the tank filler but becarefull might have lots of preasure if it makes lots or air russing noise then thats your prob and it should start again .. if not check you manifolds for heat shield missing

Do yourself a favor and take this car out to the pasture and shoot it.