Handle bars don’t return My 27 year old Raleigh had the very first Rock Shox on them. I replaced with a set that cost about $160. I also upgraded the head set with a new style clamp on stem. Everything felt great until I rode and found that when I turn, the handle bars want to stay and it takes some force to return them to the straight position. I adjusted the headset so the turning is very smooth on the work stand but again the headset feels like it wants to flop to either side. The front wheel is a lot further forward than the original Rock Shox.
Your steering geometry has obviously been messed up by the installation of the new fork.

I'm guessing the new fork is longer than the old fork.

An old RockShox suspension fork would have very little (by modern standards) travel, and the distance from axle to bottom of the head tube would not be much greater than a rigid fork. Modern forks have longer travel, are designed for bikes with higher head tubes and are significantly longer. if you put a longer fork on a frame it pushes the head tube up, increases the head angle and positions the front wheel too far forward.