Citroen Saxo juddering, loses power then stalls itself

My Saxo sometimes starts juddering and looses power. This only happens sometimes and once it starts juddering i put high revs in so it doesn't stall but even at a low gear has no power and once it comes to a stop it will die, flooding the motor. Once i then get it to start by revving it as high as possible with the key constantly on the ignition. I have looked into this before as it was a possibility of blocked fuel injectors but i have put two fuel injector flushes in and still have the problem, i have had the RAC out and everything they cleaned the throttle body and the sensor which helped for a day or two. If anyone has any solutions it would help loads! Thanks :)