A clutch that engages too suddenly (assuming it isn't a racing style five-puck installation) will be the result of the throwout bearing sticking on the tube it rides on. Had this with my E36 and could not for the life of me figure it out. Finally let a shop do the work, they had to remove the trans, not cheap (but I am),
When I was in my teens I recall driving my mom, grandfather and aunt around in my uncle's Bronco. The thing had a sticking throwout bearing, but I didn't know throwout from knockout at the time. I tried to release sooooo gradually, but the d*mm thing would go from coasting to fully engaged in a fraction of a second. I got some heat about that, and felt like sh*t, having just recently learned to drive and not knowing it wasn't my fault at all. I think my aunt mentioned something about the clutch but grandad was a bit of a tyrant and wouldn't hear of anything contradictory to what he already knew: the kid couldn't drive. Eff that, now I know better.