Most likley the clutch is not dissengauging. Are you running a new metal qudrant/cable system. If it's the factory clutch linkage, I almost garantee that is the problem.
Sounds like clutch/cable to me. I would get it checked out, previous owner had a similar situation on my current car and he let it go for too long and ended up needing to rebuild the t-5.
Is it hard to shift gears with the engine off? That's how I narrow down the problem. If the gears engage easier with the engine off, then the problem lies with clutch engagement (ie. clutch cable, like everyone else mentioned). But if the gears are still hard to engage, then the synchros or shift forks have gone south.
Um, where is the point of engagement? If it is right on the floor, that is a pretty good indication that your clutch adjustment (at a minimum) is off. Dial some slack out and see how it does.
lol, I'm having the same problem. My clutch has actually been grabbing by the floor for 2 years now (ever since I installed the new clutch). I haven't really had any problems shifting fast with it until I did the heads and cam....now I miss 2nd, 3rd frequently.