Where should I start on this?

 

Time for a clutch I'm afraid.

 

Before you replace it, check the free play first. The clutch in my old car would slip in 4th & 5th gear because there wasn't any free play in the pedal & the clutch wasn't fully engaged . Also check the bite point.

 

Alright, I'll check those things.

It's been slipping occasionally, not consistently. For an errand run a few weeks ago and again yesterday to/from work. It only happens when I try to accelerate hard in 4th/5th gears.

 

I've noticed, also, a rattling sound coming from somewhere front-side engine-bay-ish when accelerating @ low RPMs in 1st, 2nd, 3rd gears, but not so much in 4th or 5th.

I think I already know this is a real real bad sign. Right? Is my transmission dying? Now I'm hoping it's the clutch... ugh.

I checked the master/slave cylinders for leaks and couldn't find any. Brake fluid level seems normal and the clutch feels normal. It has about an inch of play before it engages. Then it depresses smoothly to the floor.