stalls when braking

[mtman]

94 gcl 4.0--abs light came on but brakes were still working but pedal was low--was going to bleed the lines when i was done fixing my cracked ex. manifold--well manifold job is done-- took the jeep for a test drive and when i stopped- the pedal went to the floor and engine stalled --made it home and stalled again when braking into driveway--reading other posts sounds like a booster problem--any way to diagnose this further---thanks