96 Jetta GL / ABA Engine.

I have no power to the LF brakes. I put the car on jack stands and let the wheels spin in first gear. I had my buddy hold down the brake(which goes to the floor) and only the RF brake grabs, while the LF spins faster. I thought it might be a booster issue because If you pump the brake pedal while stopping you get a somewhat more firm pedal. Could this be a failed master cylinder? I removed the grommet on booster because it had a small leak when I moved the vacuum hose side to side. It looked pretty bad so I'm going by the dealership to pick it up. I've also just changed the front brake pads and rotors. Although this didn't fix anything. Any help will be appreciated.

If the master cylinder is out, usually none of the brakes work. My guess would be that you have air in the line that goes to the FL. Bleed the brakes.
Are you losing fluid?

I've bled the air out of the front right. I am getting no fluid from the rear at all... I haven't located any leaks yet.

Inspect your caliper. Sometimes they freeze up.

It was the MC.