My father has a '93 F-250 with 5-speed and 300 6cyl. 165,000 miles. He recently had the trans replaced and after a week, the clutch pedal would go to the floor and stay there. It wouldn't come back up. They bled the clutch and it fixed it, but now 3 months later, it's doing it again. This time bleeding won't fix it. Anyone think maybe it's a dead master cylinder or an air leak? I tried a search for this but didn't find anything. Thanks.