Power loss and coil warning light

Hi everyone,

I own a Mondeo 52 reg, a couple of years ago I was doing a lot of motorway driving when I first experienced this problem;
after around half an hour of driving, hard excelleration to overtake makes the car notably drops power and the coil warning light flashes,
the only way to rectify this is to pull over and turn the engine off, the system resets until the same circumstances happen again.

The mechanic sorted it all out after several attempts by replacing cam sensor switch.

So I have just experienced the whole thing again and logically thought we should change the switch again however it has not worked this time.

does anyone have any suggestions????

Thanks
Rob