My first inclination is the possibility of an ABS problem. If the ABS light
is not illuminating, check to see if it "proves out" when the key is turned
on. Have the system scanned for codes. Even then, the problem may not last
long enough to generate a code and it may become necessary to compare wheel
speed sensors speeds when the problem is occuring. These sensors are
magnetic and can collect all manner of debris or there may be a poor
connection or even a cracked tone ring (the "gear" that provides the sensor
it's reference).

HTH

Try removing the fuse for the abs and see if it still does it.