Locked breaks chevy astro 2001

i just replaced the break booster for my mother 2001chevy astro van and now after pumping the breaks about 20 to 30 times the front wheel locks up any tips

If I ubderstand what you are saying, after you push the brake pedal 20-30 times the front calipers are locked ‘on’. If so the push rod of the booster may be adjusted too long and not allowing the master cylinder to fully retract. As an experiment get the front calipers to lock ‘on’, then loosen the master cylinder to booster attachment nuts (don’t disconnect the plumbing fittings) and see if the front calipers are now released.

Get back to us if the booster push rod is indeed adjusted correctly.

This is a pump driven booster correct? that means no rod adjustment too me. I am suprised that no one has yet mentioned to replace the rubber brake lines, that would be where I would start.