1993 F350 4x4 Diesel Turbo 7.3 180,000 Clutch goes to floor

So far the clutch, Master/slave cylinder, pressure plate have been replaced. After a few hundred miles, you push the clutch in and it stays.You can then pull it up by hand or with your foot and it can be pushed back to the floor with no resistance. The truck acts as if you are not doing anything(clutching). Can't go into any gear with the motor on. With the Motor running you can't get back in gear. You can turn the truck off and put it in gear and it will start moving the truck in first and you can grind through to 3rd to move to safer territory. The clutch never starts working again.This same problem has happened to the last two owners but obviously the never got it right either or I would not be having the same problem. Every mechanic seems to have the remedy but I wind up stranded. The clutch since I purchased only a few thousand miles ago has been super, super tight. So tight it will cramp your left leg. Impossible to sit through a red light. One mechanic claims that's too tight and it won't allow things to line up. His suggestion is to have clutch built that is looser and effectively disengages the pressure plate and replace the pressure plate and the Master. He is claiming the Clutch is far too strong for the master cyl. and blows it out. I can't help but think he's only guessing this might be it. This same problem happened with the previous two owners who I personally know one has passed away so I could only confirm from his wife that he did have some clutch problems. There are no smells, no visible leaks, only a small (2" ) size wet spot around the bolts of the housing to get into the clutch. It holds a drop but I never notice anything on the driveway or where the truck sat for months without moving. I only noticed this after the last clutch was put in though. It does appear that the last two times this happened was after a few 30 min to 1 hr. drives without changing gears for a while. Then when you go to downshift, you are stuck in neutral only to pull off the road. I need a permanent fix or I can't really trust taking the truck anywhere. It's never been used for heavy hauling or been abused. It's been a 45 min. driver to and from work for it's lifetime. This problem has happened about 4 to 5 times. I would appreciate any help you could offer. Thanks in advance.