1997 Pathfinder SE Clutch issues

[dupsta]

I have a 1997 Pathfinder SE 4x4 3.3LI just replaced my slave cylinder. The clutch pedal had no resistance and the slave was leaking. The new slave seems to work? When the vehicle is cold, I can bleed the hydraulics until the pedal is firm, proper freeplay, good to go. Than when I start the vehicle within seconds the clutch is not as firm and feels a bit spongy. I have bleed both master and slave. Can the heat or warmth be the issue.

I have spend so much time bleeding the hydraulics thinking it must be air. I will keep an eye on the reservoir to determine other leaks.

Just seems odd that the pedal is firm after bleeding and only after starting the car and warming it up does the clutch than get spongy?