Two things are going on that have me concerned. One issue is there seems to be a significant amount of lash in the drivetrain. If my shifts aren't smooth, the diff makes a strong "clunk" sound. Perhaps it's normal, but this is the first manual RWD performance car I've owned, so I don't know. The other issue I'm pretty sure is not normal. There are situations where the diff (or something else?) seems to slip momentarily. Usually, I'll be coasting or cruising at a steady speed, then when I give it a little gas, it will feel like it slips for a moment, then grabs with a clunk.

There doesn't appear to be anything wrong with the clutch as I don't experience any sort of slipping when accelerating from a stop. What could it be?

Still, I love this car.