My Car Jerks When I Step On The Brakes. What Can I Do?

When you apply the brakes, you feel a jerky pulsation feeling through the brake pedal and even the steering wheel. The most common cause of this sensation is warped brake rotors, and while this is only a mild irritation at slow speeds and casual driving it can become serious in an emergency stop situation and can cause unnatural wear and tear to the wheel, tyre, brakes and steering column. 

The cause of pulsation and vibration is most commonly warped brake rotors. When the brakes are applied, the brake calipers press the brake pads against the rotors that rotate with the wheel. If the rotor is warped so the surfaces are not parallel, the caliper pistons are rapidly pushed in and out as the pads contact high and low spots. These pulsations will cause the entire wheel to vibrate.
There are several causes for warped rotors. It can result from normal wearing of the rotors. It will often occur if you let the brake pads wear to the point where is there is metal-to-metal contact between pads, or what's left of them, and the rotor. Thus, the importance of routine brake pad inspections.

The amount the rotor wobbles is called the run-out. In some models pulsating will occur at just 0.001 inch, but other manufacturers allow run-out up to 0.003 inch. Determining run-out requires special equipment. If there is not too much run-out the rotors can be repaired by precision shaving away some of the rotor to make the surface smooth and even. If the run-out is too high then the rotor will need to be replaced.

If it jerks as in grabs and releases dependent on how you "step" on the brakes it will most likely be the ABS along with fresh pads. Fresh pads are always a little bitey than normal but that will change once they've been worn in.

ABS will cause the brake pedal to pulse fairly rapidly if you do trigger it.

unlikely it's a leak from the MBC as a loss in brake fluid would cause spongy braking (hard pressing on pedal but minimal stopping)

Describe the "jerk" more and you should be able to get a better answer

I am not a mechanic.

Could be any number of problems with the brakes. Maybe the anti-lock brake system since they pulse on and off to avoid skids.
Bad rotors or caliphers.
Brake fluid leak at master cylinder, other leaks anywhere in system.
Also, a car that doesnt idle properly may buck as it comes to a stop when it depends on the idle mixture to keep the engine running but you should notice the rough idle or stall when you stop.

I can almost guarantee its warped rotors you can either get them shaved or replaced

Well lets see have the brakes checked asap and check your cvc boots for cracks and tears look for lots of grease mainly look at your brakes even the brake fluid could cause a problem mainly a pull is a bad caliper could cause an accident if not looked at I had that happen once master cylinder was cracked caused me to leave the road...

When I'm coming to a stop (once in a parking spot and once while stopping at a red light) my car sort of lunges forward and sounds like it is reeving. It happens when I'm attemping to come to a complete stop. It's a big enough issue that I feel quit scared after the incident. It has happened twice in about three weeks. At the end of November I had the brakes looked at and they fixed quit a bit (850.00 dollars worth!) so I'm not sure why it is happening. The brakes are also making a squealing noise whenever I'm coming to a stop, it is a LOUD noise that can heard over the radio. It is Ford Focus 2001.