Brake question

Seem to be lots of questions with 01 Suburban brakes.....

I have this on and off problem where when I brake, right before the pedal hits bottom, there is a slight jarring or buck, almost like the anti-lock brakes are coming on. The brakes otherwise work, and this doesn't always happen every time I brake. I can go two or three stops with no problem, then maybe it happens the next time. Happens on all grades/surfaces, so it's not the ABS. Any guesses as to what this is? Thanks.

Seem to be lots of questions with 01 Suburban brakes.....

I have this on and off problem where when I brake, right before the pedal hits bottom, there is a slight jarring or buck, almost like the anti-lock brakes are coming on. The brakes otherwise work, and this doesn't always happen every time I brake. I can go two or three stops with no problem, then maybe it happens the next time. Happens on all grades/surfaces, so it's not the ABS. Any guesses as to what this is? Thanks.
Yes it could be the abs, GM had a recall in the northern states tier for a similar problem, to be sure it should be scanned with an abs function scanner to look at comparative wheel speed sensor inputs a speeds below 10.

Thanks!