I have just spent a month of Sundays on this exact issue; this is how I finally fixed it.
You need a 1 pint ball jar with two holes through the lid into which go 1/4 inch clear flex
lines about 18 inches each run to the bottom of the jar
Starting rear driver brake single bleeder, connect 1/4 inch tube and crack bleeder and
start engine. Then sieze that pedal with both hands and drive it to the floor and then quickly pull
it towards you(it pumps both ways) as fast and hard as you can repeatedly watching as the res quickly empties
fill res asnd repeat until the pint jar is full. Repeat for rear passenger. For the fronts starting
with passenger connect both hoses and crack both bleeders then really get all your frustration
out on that pedal, all the pain and frustration these dam brakes have given you. When the jar
is full close the bleeders and move on to the drivers front and repeat.
This is will work, takes 15 minutes costs a couple bucks
Good luck all