not to start anything, because i have seen what i am about to say get negative....I had a blue ox origianally and now have the hensley. i experienced what you did with the 1st hitch....now i don't worry about the trucks. As a matter of fact my 4x4 selenoid started acting up a couple of weeks ago making a crazy loud grinding sound. i would have to pull over and let it engage/disengage, then head out again. i was on a couple of hiways doing 45 in the slow lane and was being passed by truck doing 60-70 and did not have this issue(being pulled and sway)....oh and the part was a 25.00 fix, can you believe it!
For certain you need to go back through the hitch set up and adjustments. Pay careful attention to the weight distribution adjustments. Dealers aren't real good at taking the time to install these properly.
I agree with all of the other posters about putting the majority of the load over the axles. The 1/2 tons are so critical in this area.
I got tired of messing with it and moved to a larger 1 ton TV, set the equalizer up exactly as specified, and swaying and porpoising have essentially dissapeared.