I would recommend PROPER strut braces front and rear. I would also suggest that you check all the bushes out. I would guess that the rear damping / springs are all wrong as well.

What are you running (in detail, as in specific parts)?

If you want proper traction, the 6° rear beam is ESSENTIAL.

Standard diff maybe shot to pieces and not transfer power properly (would need checking out at a minimum - Marco can do this for you).