Get with RuggyBuggy on some parts.......
My Phazer he has now JUST had alot of those issues over 4K miles worth of riding and problem was fixed to a better degree, it still darted so I switched the skis to SLTs and got 1 last ride on it.
Riding on groomed, hard packed snow I could go about 52 MPH safely before it started bouncing side to side to almost being out of control- ran Curve skis (no LE on them).
I'd installed UP's steering kit, new OEM ball joints ($140 pair), Oilite A-arm bushings, spindle bushings this year- maybe 450 miles on it all.
Good luck,
Alot of pivot areas & such make it really hard to chase it to the point of "tight" without going broke.