My 8.1L would occasionally go in to limp mode. I would just throw the chassis battery disconnect switch for a few seconds and this would correct the problem by resetting the electronic control module. Happened no more than twice a year.
If the problem does return immediately, then it needs to be checked further.
If you were driving in the rain, sometimes the air intake will ingest water and cause the MAF to put the engine in to limp mode. Check the air cleaner and see if it is wet.