Car has been playing up for past couple days and today got very bad. it will struggle to start and seems to need a jump start from another car to get going sometimes manages it itself. It idles fine but under any load will cut out. hesitating and spluttering while running. go round a corner and it will very nearly cut out or die either way no power at all. if i get the car running and put my foot down it will rev ok but no increase in speed at all

It's a ford focus 1.6 auto and the fault code is P0171 it's in the garage now having a live feed to get a better idea of whats what but thought i would see how smart you guys are and what ur thoughts are.