Brakes still hard after new booster??

[Rico]

New to this but I need help and heard alot of knowledge was on here. Pedal was all of a sudden hard to push and truck didnt want to stop. After looking over and talking to people who knows more than me came up with Replacing
brake booster now have good pedal for short period goes back to hard pedal, if I keep pumping pedal comes back. Should I try to bleed again? Need some help if you have been threw before

 

[GAmes]

How about some truck info. 2nd gens have both vacuum boost and hydroboost depending on the year model.

 

[Rico]

Vacuum boost 1994 5.9 turbo 2wd

 

[MLee]

How much vacuum is being made when Idling? 22-25 is needed.