the truck has 185k on it and it's a 4x4, V6 regular cab. I replaced the clutch 10,000 miles ago (slipping badly) and when I did the job I replaced everything; flywheel, clutch kit, bearing's, master cyl, slave cly. I live in the city so it's not a dailiy driver and about 2000 miles ago it developed an issue where the pedal would slowly make it's way to the floor after I parked the truck. I would come out to find the pedal almost to the floor... I would give it some pump's and the pedal would return to position and work as it should... couple of day's later go to use the truck and the same issue. I never noticed any fluid loss though. finally, two weekends ago I re-bleed the system when at my dads house( 40 miles from mine) and I noticed some air but not much and realized the pedal needed an adjustment at the top end, so I adjusted it as well and the pedal worked great. drove home, parked the truck and it sat for 3 day's untill i needed it again. when I went out the pedal had sagged 1/2 way to the floor (no fluid loss) pumped it and it was fine and went about my day and parked it. a few day's later I went to use the truck and the pedal was at the floor. There was a small amount of fluid underneath but plenty in the resivor. I figured it to be a mast cylnder problem so I replaced it and still nothing. I even get the pedal to pump back up... i keep pumping bleeding (with assistance) and the pedal stay's glued to the floor. The slave cyl seems to be working fine when I manually pump the back of it so I assume it's good. I left some card board underneath it l;ast night to see if there are any leak's although I can't imagine there will be much if there isn't any pressure in the system.
I'm at a loss, any idea's?