I pull my sc replaced all gaskets in the process. I noticed my vacuum hose to the throttle body was getting frail and brittle. Then a couple weeks later I installed my ns1 cam. Which woke the car up a lot. I installed a new chain tensioner which I got from the dealer and since then have had issues with revs hanging. Especially in 1st. It sounds terrible like I'm not letting off the gas. The revs will jump 3 to 400 rpm up