need clutch or missing?

Like it says, i have a problem with the car seeming to just dive ever so slightly. Mainly when i'm just coasting at a constant rpm/mph, it will seem like either the clutch slips ever so slightly, or that a cyl. doesn't fire. I'm going to check the plug wires to make sure they are connected. I will probably change the clutch when i pull the tranny out, but i want to know what it is!!! Also, i'm broke, so anyone know a good place to get a clutch? i can get one refab from carquest for 100 bucks, or my friends brother bought one a bit back and doesn't need it (didn't fit on his model A he's building)
Thanks to all!!
Lee

Well, i have done the 4th gear test, and even applied the brakes, and they both go down together. I found a semi-loose plug, and shoved it in. it was the farthest(looking in) on the drivers side, so i probably didn't get it all the way when i changed wires and plugs. i still may get the clutch disk, let me know how it turns out!!! Oh, one problem with that is that i'm putting in a T5 from a 90 lx, so some of the stuff may need to be converted over.