the brakes were working i had to replace a rear brake line, from the brake junction block to the rear one and all of a sudden they were out, the pedal is sinking and when i bleed a brake the pressure keeps breaking. Heres where it gets real when i press the brake the idle drops im thinking its the booster but im not sure.

 

When you replaced the rear brake lines did you remove both rear calipers at the same time? If so, you might want to check to make sure they are installed on the correct side of the car. If the left & right rear calipers got swapped then the bleeder valve will be on the bottom and will never bleed properly. Also, did you use the proper bleed sequence?