returning / sticky brake pedal? i have a 1997 ford f350 with the 7.3 powerstroke diesel, I just had a not so great mechanic put on a new master cylinder, however the brakes are horrible the pedal slowly goes to the floor and is slow / sticky when returning. As a backyard mechanic, with experience I replaced the ABS hydraulic unit figuring that that was the problem when bleeding the driv. side front tire i am getting a never ending amount of air bubbles. ive noticed some brake fluid on the master where the reservoir meets, but that may have been from me making sure it was secured. NOW my question is: Do you think that i need a new master cylinder or a new brake booster? or what