Steering Problem

I have a weird problem on my steering that is affecting the way the car drives and i need to get it fixed as soon as possible!

Symptoms:

• Under harsh braking and turning it feels like the power steering is turning on then off then on then off quite rapidly through the full turning circle left and right making it quite hard to steer

• When driving at about 5-10 mph (12 o'clock being the wheel straight) up to 1 o'clock feels fine 1-3 feels like there's no power steering then all of a sudden it feels like it snags back into power steering and feels fine again (Same for left aswell as right)

• When driving straight the car feels as though it wanders lanes

Only things i can suspect are top mounts, coilovers or steering rack ... Or is it to be something else i cant think of??

Guidence would be greatly appreciated