Squishy brake feel with long pedal travel but brakes stop the car

Your better off going by the feel of the pedal rather than measurements. Try this. With the engine off and the brake system cold remove the key from the ignition and pump the brake pedal. it should get progressively harder and your foot travels a shorter and shorter distance until its too hard to press.
Press and hold the brake pedal hard down then start the engine. You should feel the pedal soften, that's the vacuum inside the brake booster kicking in.
Release the pedal and again press it hard down, holding it there. The pedal should feel firm and not change. Release and repeat to make sure.
If the pedal has no resistance check your work as there is no pressure in the system. If the pedal is soft or spongey re-bleed the system starting with the calliper furthest away from the reservoir.

first replace master cylinder the replace rear wheel brake cylinders.. Inspect front pads for non uniform wear, inspect front rotors replace if badly worn or scarred. You are dealing with 23-24 year old parts.

Warped rotors are usually the problem, but you cannot see? They can be measured for trueness...however with the pulling in different directions, I think your next fix would be to bleed all 4 brake lines...starting at rear farthest from the master cylinder, then other rear, then front farthest from master cylinder...lastly the front closet to the master cylinder...Pressure can feel constant, but pulling is usually caused by air in the lines...this can get worse...may not be an expensive repair if you can bleed the lines with a friend or pedal pusher system...Also check brake fluid level...was it extremely low, and you recently added some?

It is most likely you have air in the brake fluid. The first press of the pedal compresses the air and the effect lasts for a little while.
Another cause may be warped (bent) rotors, the pads can be pushed back into the calipers by the off center area of the rotor. This means that the pads have to travel further in order to contact the rotors when you press the pedal.

check your front brake pads and see if they need replaced then check your brake fluid after you change them. If you add brake fluid first you will leak brake fluid out when you compress the calipers to change the front brake pads. In the end make sure your brake master cylinder is full of dot 3 brake fluid before you drive.

That sounds like the "Porportioning valve" is defective.
You may want to go to your local library and check out a Chilton's, or some other repair manual for the "how to" to fix yourself or take it to a tech you can trust.

Check your brake light switch see if you have power in and out when you press on brake pedal if no power bad switch, if top middle brake light work's, you'll need the turn signal switch, brake light circuit run throw switch .

You have to bleed it on all 4 wheel

A sound like that that you can hear inside has to be the vacumn assist tank leaking air. Did you bleed the new master cyl ?

the brakes have to be bleed you wrote that when you start the car the pedal goes to the floor that means the booster is working fine take it back and tell them you want the brakes bleed