Steering issue

[6768chevylover]

I'm sure this issue has been brought up before. My steering has been pretty good till up to this weekend. I use to drive it every day till about 4 months ago when the tranny blew. I did a manual swap and been only driving it on weekends. Now when I drive and steer it scares the crap out of me cause it doesn't seem to want to steer until it feels like grabbing. I sway back and forth in my lane till I can control it. When I'm at a stop ill look out my window at the tires and they move on command so this is why I'm asking this question. What the hell, what is going on?