Do it wrong, do it
twice. Do it right,
do it once.
Join Date: Mar 2011
Location: New Zealand
I have lost some clutch pressure after a long run in hot weather once the engine bay cools down a bit. I had a problem with my master cylinder seals leaking so maybe your problem is also master cylinder related. Have a look to see if you can find any oil dripping off the master cylinder in the foot well area (it doesn't take much).
To counteract my problem after I reconditioned the master cylinder I put a heat shield over it.
If you haven't changed your clutch/brake fluid for a while, maybe start with that.
Other than the fluid or the master cylinder it could be your slave cylinder or something else I haven't mentioned.
Good luck finding a solution; I know clutch problems are annoying.
(Mechanical Engineer + Mechanic - Alfa)*time = ln(Bad News)