un-settled under braking

recently my car has started pulling to the right under heavy breaking, i have changed the pads and pins and it now pulls to the left, any ideas?
 
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Check your tyre pressures, I had a similar problem over summer and found one of the corners was well down.
 
Also worth looking at the front shocks, I've had a similar issue, it was dipping more drivers side stripped the brakes countless times. Turns out I have a leaking drivers side front strut!
 
If everything else fails, look at the brake distribution (maybe the right caliper is seized or the left one is not working properly).