98 blazer with near 130k. While moving forward at any amount of speed and braking the vehicle will shudder violently in a pulsing manner. The brake pedal itself will shake and push back against your foot with enough force that after a test drive my foot/leg felt fatigued. This only happens going forward, tried 2wd/4wd, while in drive and neutral and it is the same. While in reverse it does not happen at all. The front end has new ball joints, shocks and tie rods, calipers and rotors are just over 2 years old. Under a suggestion I tried unplugging all of the fuses and wires to the ABS but the issue remained. Any help would be appreciated.

 

Sounds like your front rotors may be warped... Weird how it doesn't do it in reverse though. Did you get the fronts checked? For the pedal to shake violently like that that definitely says brake issue to me though

 

I thought that too, I took it twice as fast in reverse as I could notice it happening going forward and it does not happen at all. Rotors appear great, laid them on a true flat surface and could not find any abnormality.

 

Are you sure that everything is installed properly? How are the back brakes? Does the vibration feel like it is coming from the front or the rear?