The fault is the APP Position sensors do not track well, intermittent connections to the APP or a defective pedal assy.
Here are the corrective actions;
1. Check the APP connector pins for corrosion.
2. Cycle the pedal several times and check APP1 signal at the SECM (ECM) pin B7.
3. Cycle the pedal several times and check APP2 signal at the SECM (ECM) pin B16

The foot pedal assembly uses two potentiometers to detect foot pedal position. These two signals APP1 and APP2 (accelerator pedal position 1 and 2) are sent directly to the SECM. So your code 69 is telling you that your SECM is getting mixed signals from your potentiometers.
So check your connections at the pedal to wiring harness first, then wiring harness to the SECM, and if connections are clean and tight check pin B7 / B16 at the SECM while cycling the pedal to determine if the pedal assy needs replaced. (You can also check the potentiometers at the pedal connector. Getting to the SECM is easier if you jack up the truck or remove the battery and battery box)
Hope that helps