Steering problems

i've got 17 inch center lines on mine and it does the same thing but its because the offset is so crazy that the scrub radius is way off so i just run my stock 14s with no problems. i hope this helps

the darting left to right could be play in the steering box. Could take it out by adjusting the worm gear in the box, if you have manual steering. I had a few trucks that would dart going down the road, just had to take the play out of the steering box.