Willy -

It sounds like you are locking up the brakes and that the tires are sliding.
If they are locking up unevenly, then you will experience the left-right
movement of the front end that you describe. It sounds like the brake system
components which could cause this have been replaced. With new pads &
rotors, you should ensure that they have been properly "bedded in", allowing
the mating surfaces to wear in evenly. If that was not done, you could end
up with glazing and a resultant less efficient braking.

Assuming that's not the problem - and that you're confident that it's not
the road surface causing uneven lockup, you might consider having the car
corner-balanced. This procedure requires a Porsche-knowledgeable shop with
scales. They will fine-tune the ride-height adjustments to ensure that the
weight distribution is correct at each wheel. This will interact with your
alignment so it will need to be checked and readjusted, as necessary,
afterward.

regards,

The wheel that locks up either has a bent or clogged brake line , most
likely a clogg ....THIS is why we change the brake fluid out every year or
so....change out the line (all lines ) to the locking wheel

Just out of curiosity, since you did not change the master cylinder, why
would you not consider that it might be that causing you the problems.  Have
you had that checked.