Clutch question

[legendarysnail]

About 6 months ago I had the clutch on my '93 Coupe replaced. It was about $500 total for an OEM-equivelant clutch, all parts, and labor.

When I first got the car back it was slipping bad and the pedal was a lot lighter than brfore, like if I floored it in 4th gear going 45mph, it'd completely slip and go nowhere. So I drove it back to my mechanic and had him adjust it to what I thought was normal. I was happy for the first few weeks until I drove it hard for the first time (it is fine under normal driving). If I launch it above 4000 rpm, it wil slip pretty bad, if I shift fast it'll slip (powershifting makes it slip even more), and if I'm trying to do certain maneuvers (like flooring it directly after a u-turn) it'll slip even worse.

It's a brand new clutch, and if it is really OEM-equivelant, it shouldn't be doing this. So I've come up with 3 conclusions: either my mechanic doesn't have it adjusted properly, the clutch was bad from the factory, or it's installed incorrectly. I really want this thing fixed because I can't have much fun in it anymore, let alone take it to a drag strip or something.

I've been too busy to take it up to my mechanic, but it's getting worse now. The problem is I don't know what to say to my (former) mechanic because he's so full of himself and doesn't think he can possibly screw something up (for example, I had him install new OE Nissan rear brake pads, and now my e-brake squeals all to hell. I confronted him with it and he says tough luck buddy, you supplied the brake pads).

So can anyone help me out here? I've tried adjusting the freeplay, but that does no good. It's really starting to get annoying, not to mention slipping worse.