I have a 2005 Excursion with a 6.0 powerstroke. About a month about I got the flashing. Tow haul and check I guage with a pegged trans gauge. Went to Ford baught a sensor and SP fluid along with filters and changed it. This did not cure the issue. When truck is cold no code no issues. When truck is running down the highway no code no issues. As soon as I hit stop and go the lights flash and it blows the check engine light. Finally at my wits end with it I took it into Aamco this week. (Have a good friend there) They ran tests and came to the conclusion it was the internal transmission harness. $660 later I pick up my truck and bout 5 miles in same symptoms. I've asked on the Facebook 6.0 pages and all over but seems no one has ever heard of this...... I find that weird as 6.0s are full of similar issues. Any help would be much appreciated.