[snowload]

2002 Ford F250 Truck with 5.4L V8. The ABS light flashes and the speedo spikes down and the truck runs rough. One coil has been replaced and rearend speed sensor replaced.
Problem still exsist. How do you fix it?

[TxGreaseMonkey]

When the VSS in the differential goes, the dash often lights up like a Christmas tree, a host of codes are thrown, and the truck barely limps along. Usually, if you replace the VSS and clear the codes, with a code reader, the problem goes away.

[snowload]

When the VSS in the differential goes, the dash often lights up like a Christmas tree, a host of codes are thrown, and the truck barely limps along. Usually, if you replace the VSS and clear the codes, with a code reader, the problem goes away.

First time it coded, bad coil. Replaced it. Did not fit the problem.
Did not code anymore, Replaced VSS in the diff.
Did not fix the problem, still no codes.
What now?

[TxGreaseMonkey]

Even though the CEL doesn't come on, have you checked for intermittent codes--they may still reside in memory. If there are any codes, they may give you direction.

ABS lights often come on any time a "hard" code is thrown that triggers the CEL. Intermittent codes don't always trigger the CEL.