New clutch and cable issues

[hoffmandirt]

I recently replaced the clutch, throwout bearing, pressure plate, and clutch cable in my 1999 Subaru Impreza because the cable was adjusted as far as it could go and the clutch was slipping. When I removed the old clutch it looked like it still had some life left in it, but I replaced it since I had it apart.

I put it all back together and the clutch still feels like it doesn't exist. Everytime someone else drives my car, they come back saying I need a new clutch. I have to heavily slip the clutch to pull out and the transmission grinds every so often when putting the car into first gear. I also get shuddering every so often when I pull out. I did not get the flywheel resurfaced and I assumed the clutch would eventually wear, but I put on over 5k miles already and I am still getting shudder. What is going on?

My assumptions:

Purchased a junk clutch
Bad flywheel?
Junk clutch cable. It was $30.00 and not oem subaru
Oil leak on clutch
Bad transmission

The car has 170k miles on it.