Sticky 5th and 6th gear (manual trans)
 

I was cruising for 15mi going 80mph in 6th gear before I downshifted to 5th. Suddenly it felt sticky or sluggish, not the car, but the gearbox. Went back to 6th and it was doing it again.

Eventually I came to a stop and when I rowed through 5th and 6th it was fine, then after a couple more miles it was doing it again. It engaged perfectly, but the gear lever has more resistance, it's only happening between 5th and 6th.