Still having brake issues..

[KickinPups2]

So Im at a lost for what's happening with my brakes...wondering if anyone has had this problem
1)After a break pad change my breaks became really squishy to the point of not being to stop safely (Took it to my mech he said looks like master cylinder is no good) I later replaced master cylinder myself did all proper procedures bench bleed etc and bleed all four lines in the correct order as the mach manual states DSR-PSR-PS-DS...After this failed I brought it to a different garage they did a bleed said everything was fine and it was good for about two weeks..They said no lines are cracked or bleeding.

2)Well after another month they got squishy again I did another bleed and they were great. I did notice some wear on the PS rear rotor but all pads are still over 50% now there squishy again to the point where I feel I have to pump them to stop. Don't get me wrong The breaks are there but so squishy. I sat in my garage tonight to see if any pressure built up I could push them to floor but it did become solid after 2-3 pumps..I just don't see how there could still be that much air in the system I legit have bleed over 2 liters of brake fluid.

3)Now I have heard some people saying air might have gotten into the ABS..Yet I just don't see how unless I screwed up during the master cylinder install... I'm at the point of just replacing all the rotors and the calipers and pads and lines just to see but that's easly over $700 and I would like to avoid that unless it's the last result..So any suggestions would be great

[splix]

You have a leak somewhere. Air is getting into your lines.

[KickinPups2]

So should I just do a line replacement? I have some old stock 07 G35 lines from when I did my Brembo upgrade anyone know if they will work on 07m35x?

[SchoonerVanHelmet]

When you say you replaced the brake pads, did you:

1) Resurface the rotors or replace the rotors?
2) When you compressed the calipers to replace the pad, did you open the bleed valve screw on the caliper (to allow fluid to drain from the caliper when compressing) first so you did not force air or back pressure fluid into the portion valve / ABS system?
3) I was alway taught to bleed the PR, DR, PF, DF ( which is the farthest point working toward the shortest point from the master cylinder)
4) Did you confirm the proper brake fluid was used?
5) How much brake fluid did you replace?

I'm not a certified mechanic, just thought I would throw out a few questions.