Please understand diagnosing your issue by exchanging messages is not an exact science, but yes it sounds like you have air high up in the system. Not necessarily lots of air, but if you let the master cylinder reservoir suck air you have to purge the entire system to get it out.

alright now is there any distinguishable differences between having air in the line as opposed to having a faulty master cylinder that i would be able to tell by testing or trying out something. also advanced auto parts has a master cylinder unit without the reservoir on it for only $55 as opposed to 145 for the new unit do you think that is something that would be easy enough for a guy with a simple rachet set wrenches and a 300 piece screw driver set? just in case it does happen to be that

If you pump the brakes till they are firm, then hold the peddle. If it stays, it'* air in the system. If it doesn't stay firm, the master cylinder is leaking fluid past the piston.

okay it doesn't stay firm it slowly goes back to the floor. is there a cheaper fix other than replacing the master cylinder

Sorry, no. A master cylinder either works, or it don't. Not much you can do other then rebuild it or replace it.

okay and how much work is involved in re-building it also do you have to have alot of knowledge to be able to do it because im pretty new working on brakes also thanks so much for all the help guys i knew i could count on you to figure it out

Without a lot of knowledge you would be better off replacing the master cylinder. They cost about $55 at autozone, and $32 at RockAuto Auto Parts Brakes are something you really don't want to cut corners on. Do it right, your life may depend on it.

If you buy at rock auto, make sure you use our discount code.

https://www.gmforum.com/t279335/

That code is expired. Time for a new one.