This is the most likely culprit from an internet diagnosis stand point. FYI... the tranny needs to be dropped to get to the CSC. Consider upgrading to a heavy duty CSC or the external slave conversion sold by Z1 so that you do not have to drop the bell housing in the future to replace this notorious item. If your clutch disc is also getting close to needing replacement you may also want to do that while your at it because the CSC must be replaced when you do a clutch job too.