Oh $#!& I might have made have made a horrible mistake. I bought an iron rock off-road 3 link kit for my truck. All the research I did indicated that a well designed 3 link is just as stable on the highway or while towing. In fact many seem to believe that longer arms that are more parallel to the road ride better period.
I might be misunderstanding the differences here. I had always thought that a 3 link could be stable on the highway and while towing as long as the geometry was set up correctly. Things like link separation, caster, track bar angle, and joint condition seem to matter a lot for how the front end behaves under load.
It makes sense to me that a poorly designed or worn 3 link could feel loose, especially with tongue weight on the back of the truck. But I had assumed that a well laid out long arm 3 link would track straight and handle towing without any drama.
If there is something specific about the 3 link layout that makes it inherently less stable at highway speed or with a trailer, I would actually like to understand that better. I'm still trying to wrap my head around what part of the geometry would cause that.