I was running the unleashed performance tune from Torrie and went into limp mode while towing my bass boat. Ihave it too much throttle and (without going full into mechanic mode) I just stopped and restarted my truck. It fixed the limp mode.
I ended up needing my whole rear diff replaced...
I have also ran into this issue while towing my bass boat and running a tune. All you have to do is turn the truck off and turn it back on to reset the issue for the time being.
note: I was running my performance tune instead of the towing tune when this occurred.