1992 f150, new clutch master and new external slave... Got it all on and pumped the pedal till my leg was about ready to fall off and had a good firm clutch pedal, start the truck up and shift about two times and I'm back to no clutch.. Repeat the process of pumping the clutch fill its firm then it'll shift about two times and then nothing again.. Did I get a faulty master or what's going on here?