This is a common problem with these abs systems. Find a competent shop with a scan tool that can sequence (exercise) the abs system. This is necessary to eleminate all the air. I bought a suburban, well maintained and cared for, the neighbor I got it from said it has always had a low pedal. They tell me thats normal on these trucks. After getting the system bled with a scanner it was better- not as soft but still kinda low pedal. Harking back to oldentimes I put a good tight shoe adjustment on the rear drums and that improved the pedal height a bunch. It wasnt a high firm pedal but it was a pretty high firm pedal. Something I could live with, so to speak.