Im having some issues with my brakes.I have speed bleeders and ive bleed them a few times in the last few days thinking i just have air in the lines but i think my master cylinder is going out.I have a mushy pedal and every time im stopped and i push in the pedal in and then let off the rpms rise a few hundred then drop.Is this a sign of the master cylinder going out?Thanks in advance

 

the rpm rising and falling when you pump the brakes is normal...thats the brake booster doing its job.

if you have a noticeably mushy pedal and arent leaking fluid, replace the master..