So I'm having a terrible problem with my car that is driving me crazy.
Since I've been driving it, it's been doing it. It's like there's air in the lines, the pedal will almost go all the way down, and sometimes the brakes don't even catch. When the brakes do catch sometimes it'll be hard then go mushy and go to the floor.
Mind you this is only when the car is running, and it's just fine when it's not running.
I've bled the brake system, replaced the calipers and pads, replaced the whole drum brake assembly and it's not getting any better.

Any help with this would be great, since I don't know what to do next.
Besides me driving around like this is dangerous.

 

Your master cylinder may be bad.

 

If you are sure that the brake system has been thoroughly and properly bled, then I agree with Kommando. Replacing the master cylinder should be the fix.

 

Since you already answered the: "How bad is it?" question. Get a new Brake Master Cylinder. If you car was an Aircraft ... you'd be GROUNDED! Don't get killed or kill someone else over hesitating to replace a Brake Master Cylinder. Get it done and ... "Give everybody a brake!"

 

The master cylinder is the one that you pour the brake fluid into that's on the fire wall right?

I'll take the one off my parts car and put in on and see if that fixes it, if not I'll be back.