Experiencing really weird feeling in my clutch. I just turned 100k miles. The clutch is not slipping and I've even put it in a high gear going up a hill at slow speed to see if it does, but it bites fine. But when I'm really on the acceleration, and shifting at high rpms, I notice that the clutch pedal starts to get spongy and not pop back up as quickly. I've read some things about the clutch slave cylinder needing to be removed and cleaned, but wanted to see if anyone out there has experienced the same and if they found a solution.

(Btw, I was curious about new clutch replacement cost and apparently 6MT has an "integrated flywheel" and if the clutch goes, so does the fly. Best estimate I found for new clutch and flywheel with install was $1500! Trying to avoid that obviously.)