What year was your Suburban again? Mine is a 1995 K2500 and there is a TSB 99-05-24-001 out for the metering block attached to the ABS that was making the truck use 90% of its front circuit for braking and essentially ignoring the complete rear circuit. That was why my Suburban at 120,000 miles has all of its rear brake shoes intact. They hadn't touched the inside of the rear drums in two decades. Once we replaced that metering block, things worked a lot better. Here is the TSB article:
Covers 1992 to 1999 Chevrolet & GMC C/K Cab Chassis, CrewCab, Pickup and Suburban as well as 1996 to 1999 G Series Vans (TSB 99-05-24-001, June 1999)
http://www.dieselplace.com/forum/63-gm-d...5-24-001-a.html
http://www.amazon.com/ACDelco-125482.../dp/B000S2RYZE (1995 and newer valve)