OK here is the easy way to see if it is the booster.

1. With car off pump the brake pedal until it does not move any further down.

2. Turn on the car

3. If the pedal goes down immediately, then the booster is OK, if it does not go down at all or slowly, then either the booster is bad with a torn diaphram, or you are not getting vacuum from the motor.

4. If it did not move, first check the vacuum line to the booster to ensure that it is pulling vacuum when the motor is running. Can also check by disconnecting the vac line with motor just shut off and residual vacuum should give you good bleed-down whoosh.

No cost, and a 30 second check will either confirm that this is part of the problem or not.

Cheers,

Steve

P.S. In anycase get the CV fixed

 

Aw, yeah, the booster! Duh, why didn't I think of that? Good thinking.