I had the same problem with my clutch. I adjusted the cable at the tranny several times. The clutch would feel good for a couple of days then would change again. I finally ordered another cable. When I pulled out the old cable, this is what I found:
By the way, there is an easy way to install the pedal cluster clutch spring. You need to remove all four nuts that hold down the cluster, detach the master cylinder linkage, then remove the allen head bolt from the brace that attaches to the cluster. Lift the cluster about a half inch off the floor then pull the clutch pedal towards you; the spring pin on the clutch pedal rotates to the floor. Now, just slip on the spring. When you push the clutch pedal back, it will pop into position. Now bolt it all back down. Done!