Hey I got a 05 sti just ran into the same problem but little bit different situation. My clutch got really soft and then stiff then softer until the pedal finally stuck and I lost my clutch. I smelled a heavy dosage of burnt clutch and I check the master cylinder and there was no fluids left. My master cylinder gave out and had to replace that. Just an idea to help you out man hope its not too serious of a problem!