92 Fullsize with brake problems
 

any fluid leaking? check all connections and lines for leaks. check master in the engine compartment and under the dash for any wetness. also deteriorated rubber lines can give you a spongy pedal (this you won't see it happens from the inside). if the rubber lines look cracked or dry rotted you may want to replace them anyways.

ou may have to replace the ABS unit under the hood. My sons 92 did the same thing as yours. Got a used one at a salvage yard. Put it on, then the ABS light went out. Then about 2 weeks later. The brake light came on and hardly no brakes at all. Checked the master cylinder and it was almost empty. Had to replace the front pads. They were about gone. Then we checked the back brakes. Had a wheel cylinder leaking really bad. Replaced both of them. Bleed the brakes, brake light is off. And the brakes are great. gearyr

billymac49,
No fluid was leaking anywhere. I forgot to mention that all the brake lines to the calipers and the rear were replaced with stainless steel braided lines.

sounds like there is still air in the system..Try bleeding your brakes starting at the right rear,then left and do the same up front..Right side then left...Make sure you keep the master cylinder full or you will suck in air and have to do it over..