I have a 1997 f150 xl v6 4.6 only rear abs. My problem is that my rear wheels (specifically passenger side locks up before the rest and my brake shimmy on the wheel is ridiculous even with all new rotors/drums last summer. They feel like they should when u push the pedal but the back is grabbing before the front. Heres some details

ABS is ON and 9 flashes for the code
ive replaced Masyer cylinder, all lines in back and rubber hose, rear wheel cylinders, rear abs sensor on rearend(3 times) and swapped out my proportioning valve from a truck same year and model that was in a junkyard.

We are debating selling the truck over this

 

Have your new (last summer) rotors and drums machined, sounds like they are warped and out of round. Can't help with the ABS code, need a manual for that info.

 

Sell it !!!