I am having the same issue with my 2006, except it is with the R/R sensor. It has been replaced twice, problem still persists.
I was sick of the problem, so I bought an entire used ABS/RSC controller off of Ebay($107) to see if that was the issue. I tried ohming the 2 R/R sensor wires before swapping the unit and was getting inconsistant readings. I swapped units anyway, and within 5 miles the same R/R sensor code appeared.
When the problem first started happening, the ABS unit was actually applying the brakes and vitually stopping the truck at slow speeds(freaked out my wife). I'm usually pretty confident in Fords wiring harnesses, but I am leading toward a harness issue.
I need to research the path of the harness from front to rear, you cant see much of it, maybe the harnesss is built in multiple pieces and has a connector between them, possible corrosion issue.
LE