Recently changed a master cylinder because it died in the middle of town, internal seal cracked. Bled the abs and the lines between that and the master well enough. Now all four brakes will drag more the more i drive, usually within 10 to 15 minutes. Removing the brake booster hose is the the only consistent-ish fix i can get. I tried using washers to shim the master cylinder out almost 1/4 an inch from the booster (non adjustable pushrod there), this didn't seem to do anything. I returned the first brand new master cylinder assuming this was the problem and it did not change at all. I am assuming that the pushrod of the booster is engaging the cylinder too much but im not wholly sure. Honestly no f*** clue what to do.

 

If removing the vacuum hose from the booster "fixes" the problem, it sounds to me like the booster is defective.

My first thought was definitely the pushrod being too long, but it sounds like you eliminated that possibility.

 

So the master cylinder you used is not the same as the one that broke down?
Will need the correct replacement else is will have pressure on the brakes all the time or the braking action is not correct. In any case I would never use an improper replacement for the brakes.