i just got an F150 supercrew 5.4L 4x4. has approximately 180k miles but motor and tranny run clean and smooth. issue i am having is the OD light flashes but no other service light is on. i had code read and said it was a Differential Feedback Pressure Sensor (DFPS). Replaced the sensor and hoses but still the light is flashing. i have not changed EGR as of yet due to money but was wondering if i could maybe get pointed in the right direction. the Tranny does not seem to be operating improperly except at low speeds it tends to shift between OD and 3rd on occasion.
I'd love any feedback on where and what to look for. thanks alot guys and gals.

 

First, the OD lamp indicates an issue with the electrics on the transmission.
It has nothing to do with the DPFE or EGR system.
You have two separate troubles.
List the codes you get.
The trans codes should be in the 7xx range.
The EGR code should be in 4xx range.
What are they?
Good luck.