Spongy Saab 9.3 Brakes

My 99 Saab 9.3 brakes are spongy and even when pushed to limit provide poor braking performance. They take at least twice their normal distance to stop, will not engage the ABS or lock the brakes. Pumping has no effect. Has about 130K.

To date

Found and replaced leaking metal brake line to rear?power bled all four wheels

Inspected calipers slides ?free and working as are wheel cylinders. Pads and rotors OK No additional leaks. Rubber brake lines seem to be functioning without bulges.

Brake performance un-changed.

Installed new master cylinder ?power bled the system with different color fluid.

Checked power boost by pumping brakes ?holding petal while starting motor and observing pedal drop a couple of inches

Power bled the system again and again (No air in system last three bleeds)

Brake performance un-changed.

Luckily I have another vehicle

Any suggestions will be appreciated. What next?

Did you bench bleed the master cylinder before you installed it ? It sounds like your master cylinder has air in it. You might want to rethink the rubber brake hoses. If one is weak it will affect the entire system.