ZF6HP26 Archives - Transmission Digest
An Inflated Story about Erratic Shifting

After a wide-open throttle forced downshift and then coming to a stop, the vehicle would take off in third or fourth gear. A scan tool confirmed that the wrong gear starts were commanded by the TCM. The transmission would upshift from third or fourth gear to fifth and sixth gears.

Ford 6R60/6R80 Component Upgrades, Part 2

The second part of this two-part presentation involves planetaries, filter and valve body.