I'm with Uman on the clutch adjustment, but you need to inspect the inner hub and basket for chatter marks and grooves. That would be another problem of the lurching. Pretty predictable since you said there is no more adjustment with the perch.
As for the intake, it sounds like the toomey set up. Not a bad filter as long as you have an outerwear. Just don't think you're going snorkeling with the big 4X4's.
The skid plate. I like the PRM I have but it is a bit bulky. The new stuff from JDS is pretty cool. It's little guards that go around the sprocket and rotor. Pretty trick.