how to fix my Transit 2.4 Diesel Cluch?

Transit 1992 diesel 2.4/2.5 trader 80
while driving the clutch "cable" looses all its ajustment but as you release the pressure of the clutch pedal doing so twice it rejusts it self and works as normal this has happend twice to me now.There is no sign of clutch ware no drag or slip pulls well.i have purchase a new cable but do not feel that this will solve the problem any help or imformation would be appreciated.
Regards Pete