im Driving in the high way every time im on either 4th or 5th gear from 3000 to 4000 rpm the rpm goes to 4000 then drops back to 3000 rpms then shoot up back to 4ooo but the rpm goes up slow. Im tryin to figure out what the problem is maybe you guys can give me ideas right now i have a Hks filter and S-Afc. it was never doing this problem before.

 

sounds like the clutch is slipping