91camarox

Hi so I had really bad front pads I just changed them yesterday. Today i took it for a first drive and it won't move in reverse or drive without some gas. I then checked that I put it together right with force I can spin the wheels myself. I had someone help me bleed them I also did the pistons again. The weird part is while I drive it is stiff but I can slam brakes real fast and then instantly off and they feel perfectly fine. it will even move in reverse and drive without gas. My dad believes one of my calipers may be bad or my master cylinder only mistake made during install was when didn't take out some brake fluid before compressing pistons im not sure where to start because now it seems fine... also its a 91 camaro rs