when cold injector warning and throttle is either on or off

[mike150256]

had to create a new account as i cant get in.
my megane 54 plate dynamic 1.6 16v vvt has developed an annoying problem when cold. occasionally on starting from cold i get a warning for injector faults, when this happens the accelorator is eith on or off to max for approx 30 secomds then it settles. my dad is/was a senior technician, he has plugged his code machine and gets injector fault/ pressure fault accelerator fault. we have replaced the accelerator sensor also the complete fuel rail /injectors / pressure sensor all from a very low mileage ( 32k ) damaged car that was hit in the back. although it has improved slightly the fault is still there, once all the fault codes are clear the car runs perfectly for about a week, then it starts again. obviously an intermittent fault on a sensor but not sure where to look. anyone had or know of this problem or how to rectify it?? any ideas would be great

thanks

mike