brake pedalwhen you first step on it goes all the down second time it goes up on 1998 Ford Explorer

i put in new pads rotars,calibers and master cylinder brake pedal still goes down first time you step on it Has been bled afew times Im lost????

Asked by for the 1998 Ford Explorer
Check to make sure that you didnt put the left caliper on the right side and vice versa. The bleeder screws should be at a high point on the caliper, if they are low on the caliper you will never get the air out. Air always travels to the highest point. Also, did you bleed the new master cylinder before you installed it? Did you follow the proper 4 wheel bleeding procedure for your vehicle?
I spoke to the mech and he said he did it right could it be the abs system????
Yes there could be air trapped in the ABS unit. Your mechanic needs to look up and follow the proper bleeding procedure for your vehicle.