severly pulls to the left when accelarating

Help please!!! My 2001 laguna estate severly pulls to the left when accelarating and when you lift of the power it pulls to the right!!Also, if you hit a pothole etc on the road, the steering is very unpredictable. ive notised that there is a sensor of some sort attached to the n/s/f bottom arm, could this be at fault? or does this model have a steering sensor?? any help much appreciated as i love the car but cannot live with these faults.

hi i had this problem with my old car and it was the back bushes causing it i had them replaced and the problem was fixed hope this helps