Clutch slipping

I have a 1984 Toyota 2WD pickup with 165k miles.

I replaced the clutch in January because it was slipping pretty bad. I put in a kit including pilot bearing, pressure plate and clutch. Bearings were replaced, flywheel was resurfaced, and everthing went back together without too much trouble.
Also, the master and slave clutch cylinders have been replaced in the last 6 months.

Since replacement, when the weather is cool (below 50 degrees) and the engine is cold, the clutch functions as it should. It passes the stall test in 4th gear (hold the brake, let out the clutch, engine dies in less than 5 seconds). Once the engine warms up the clutch begins to slip typically on the way home from work. I can floor it in second gear and have the clutch slip. Let of the gas and it will jerk a little and reengage. The next morning when it is again cold, I can drive it to work and it functions fine, but on the way home, it slips again.

I am unsure if it is a lubrication issue with the clutch plate or what one person suggested: the plate may be in backwards. I fix this thing myself because I enjoy getting my hands dirty. My quesiton is this: When I take it apart again next weekend, what are the telltale signs I should look for and is there something else that has not been considered? Any suggestions or expertise would be greatly appreciated.

-R