I have a 2002 K2500 Extra Cab Silverado. Since I rotated the tires recently the antilock brakes are acting weird. When I come to a stop, either slow or fast, at about 2 MPH the right front starts pulsing like im on Ice. Did I knock off a sensor or something? Where and what should I look for?

do u have a way of retrieving the dtc's?

This may sound odd but put the tires back to the same position before rotating them. See if the problem goes away... believe it or not uneven wear or incorrect tire pressure will upset the rotation pulses from the sensors.
Or...
You have have inadvertently knocked a sensor.