1999 Mercury Sable shoots out the power steering fluid

Steering problem
1999 Mercury Sable 6 cyl Front Wheel Drive

This car started to leak power steering fluid really bad. It would when first started have normal fluid level. After driving it for a few miles the fluid level would drop to the bottom of the pump and get hard to steer. When shutting the engine off the fluid would squirt out of the breather hole and cover the motor in fluid. After a cool down the fluid level would be about normal except for the amount that sprayed out. I put in a junkyard pump which acted the same. The primary leak was coming from the passenger side of the rack and pinion. I bought a rebuilt one installed it and the same problem occured. I pulled the check valve in the pump and replaced the o ring. One more thing is the oil gets foamy. After working the wheel the foam clears up. But again after driving for 10 or so minutes the fluid level drops and the oils is cavitating, then shut down and oil again sprays out of the fill cap.