Towing problems

[RL06]

Im new to this site and new to the 6.0 powerstroke. Last weekend i was pulling a boat about 7000 lbs and as i got on the interstate, my truck went into a limp mode where it wouldnt accelarate past 55mph. wrench light came on so i pulled over and there seemed to be a dripping of transmission fluid from underneath. turned the truck back on and wrench light was gone and no drip but just went back home. any ideas to why a sudden loss of power.