You might want to check out EGR Brakes:
http://www.egrbrakes.com/
I just put a set of there big calipers on my 1996 Tahoe. I also have a rear disc conversion kit from them that I am having installed next week.
Just the fronts made a huge diffrence in my stopping ability.
Your problem sounds like it might be a ABS related issue though, but your big Suburban will definatly benefit from more heavy duty brakes like these.