so ive had this problem with my 2001 F150 for quite a few years now.........Back about 4 years ago, i had the sinking pedal issue......Changed out master cylinder....all 4 calipers.....bled everything....Still had the issue. Finally swapped out the abs unsit and it fixed the sinking problem.Ever since then, it feels like most of the stopping power is in the front and that the rear discs are barely working.Im wondering if they sold me the worng master cylinder? I do have the flow control fitting on the rear port......But im not sure if its supposed to be there in a rear disc setup. Can someone take a look at there master sylinder that has 4 wheel disc setup and see if they have that valve on there?
Thanks
Rich