My 2003 F150xlt acts up at times in reverse. The engine will rev up n down and the truck backs up jerky till it dies. Not sure why it does this at times. Any ideas be great. It's a 4.6 v8 with 280,000 miles.

 

Check the truck for codes
The harness is chaffing?
The engine moving around on bad motor mounts?
Maybe check a few pids and see if any of the powers or grounds are intermittent
Doubt it is the problem, but check a few grounds like the ones behind both kick panels and the ones out by the battery
Wiggle test the harness and engine loom in particular
Check a few of the transmission pids in something is wrong there
Good luck

 

I wouldn’t rule out the torque converter.