They all cough and splutter at low revs, its the map on the ecu.

Ive had a couple. First one ate the speedo sensors in the gearbox, the box itself was stiff to get into certain gears, the instrument cluster lighting kept randomnly failing. I crashed that one into the back of another car at 15 - 20mph and it bent the chassis legs beyond repair. Second one broke the DSi clip for the IRMC fixed it but still made a weird noise, ate wheel bearings, clutch cylinder went. Not the most reliable Focus.