I had a friend who bought a 2016 2.7 and said it could barely hold speed towing his 7500 lb GVWR trailer. He then went and traded it in on a 2018 3.5EB and said he still has trouble. It would slow down to 55mph on climbs. I have no idea wtf he is doing, but my first comment to him was maybe its overheating and he said no. Then I told him the intake temps are probably ridiculously high.
My truck has never had that issue. It def gets hot and you can feel it cutting power, but it was never enough to slow me down.