Timo
I kind of had the same problem on my 92 F150 4.9L Clutch. I heard a loud pop and the clutch wouldn't release all the way. Well I went to the Ford Dealer and got new bushings and replace them. Well after I replace them it still didn't fully release. The clutch worked just find but wouldn't release all the way. Maybe about a 1/2-3/4" Short of all the way out. Well I got to looking around and found that the release spring was lying under the park brake bracket. The tang that held the spring in place broke off and dropped down. I could replace the entire clutch pedal assy, but I opted to just add a spring from the Help Section in Autozone. About $5.00 dollars for a pack of misc springs, I bent one to fint and it works as good as new. I hope this helps.

Kevin