Looking for answers and nothing comes up for my situation

Driving down the road the steering wheel jerks/jumps to the left
Constantly to where if I was to let the wheel go it would work its way to the other side of the road.
Only happens as I'm trying to drive straight. As I turn it doesn't do it.

It started about a year ago for the first time and would happen about one a month or so. but it always seemed to go away after I stoped to look at it, or I just left it because I was pissed.

Now today it really pissed me off being i was trying to get to the hospital to see
My grandma about about 40mile drive and all the way there it jerked and shook all the way. It pulls and jumps and its constant almost like a flat tire.

I have video of what it does but not sure how to upload off Iphone. If anyone knows what is going on or needs to see a video please let me know something. Or how to post
The video
35x12.5x20 tires
Wheels balanced
Alignment done
Pinion rack new 14months ago with new tie rod ends
New belt
Power steering fluid full, not a single leak in any lines

 

Wheel bearings. Ball joints. Loose or worn suspension bushing. Try a steering stabilizer.