Brake pedal hard and vehicle wont stop. intermittently

You have a blown power booster. It is leaking vacuum and you will have a hard brake pedal and find it tough to stop your vehicle. Replace the power booster and you will have brakes and no more leaking air sound.

Check all wheel sensors for broken wires, loose connectors or position of sensors in their mounting brackets.

If the ABS system were the problem, the ABS warning light should come on.
So I would say the problem is with the vac booster. The booster is between the pedal and the master cylinder. It uses vac to boost the pressure applied to the master cylinder by your foot.
You may have to leave the vehicle with a mechanic to drive until the problem occurs.

Sounds like your master cylinder is bad on your brake system. If you are stopped in your driveway(not on the street) leave the vehicle in park. Start the car and place your foot on the brake with light pressure and keep this pressure on the pedal. If the pedal continues to drop slowly to the floorboard your master cylinder is leaking past the primary piston in the master cylinder. If this is the case have this repaired immediately. Your brakes could just all of a sudden not be there the next time you apply them when you need to stop.

You have to bleed it on all 4 wheel

You need to bleed the brake lines.....I can tell you how if need be.

check for brake booster hose off

if you can tap accelrator and idle lowers it is a problem with cable sticking