braking

Can you tell if it actually is the ABS kicking in or if it could be severely distorted rotors. The best way to tell is by what speed it happens. If you feel it more at higher speeds, that tends to point toward a brake rotor problem. ABS issues tend to show up at lower speeds.

at slow speeds the brake pedal pumps, and at faster speeds it feels like the front end is falling apart, the front rotors and pads where just changed

Bring it back to the guy that did the brakes because there seems to be a problem there.

i did them,, the problem was there before i did the brake the job. i replaced both front rotors and pads , and one caliper bracket with 2 guide pins. also noticed that it was a strain to collapse the pistons on the calipers

You could have an overheating issue or the problem could actually be coming from the rear brakes. It needs to be inspected more closely. A dial indicator can be used to check rotor runout.