probably your abs relay is gone its located on the passenger side near your transmission tunel under the dash theres 4 or 5 relays there i think its the purple one mind you theres two purple ones but they are the same.
my mate gaz had the same problem with his 4x4 sapph fitted new relay and all was fine. cant believe a car with that much power has these problems incredible!

hope this helps mate any more help just ask !