Shifting problem still occurs, please help!!

[Aetos]

Problem: Shifting quickly is IMPOSSIBLE in my car. If you press the clutch in and try to shift into any gear you either get a "block" for about a split second before it goes into gear. If you don't get the "block" you hear a high pitch/clunk sound coming from underneath the shifter or somewhere there. They both let you engage the gears, but its not smooth or safe sounding.

Here is the catch though, it only happens during the first time you shift into gear with the clutch down... to put it easier:

1) press clutch
2) Engage into gear quickly and get the block
3) DO NOT RELEASE CLUTCH
4) Go into any other gear and its completely smooth, no matter how many times you shift. It will be like a knife slicing through butter going into gears.
5) release clutch
6) press clutch down again and process repeats

If you shift slowly and let the gear "suck" the shifter in and just ease it into gear (2-3 seconds), the gear will engage with no apparent sound, but the block is still there, but after a bit the shifter will just slide into the gear.

Attempts to fix problem:
1) New transmission fluid
2) New GM master
3) Drill mod
4) New Hydraulic fluid

Edit: I have also done the clutch slipping tests.

Revving to 5-6k at a stop with clutch down does not move my car at all.
Hitting the throttle at around 20mph in 4th has a steady increase of rpm/mph, not a wide variation between them.

[Aetos]

Update: Took the car to a mechanic I know so he can drive it around a bit and try to tell me the problem. He came to the conclusion thats its probably one of three things; air in the slave, the slave itself may be going bad, or the pressure plate may be bad. He said the sound that emits during shifting is the clutch.

I just ordered a mity vac to try and bleed it out. If that doesn't work, I have a brand new slave sitting in my hatch(reluctant to drop the tranny). If that doesn't work either, I guess Im gonna be ordering the LS7 clutch.