My car is having problems idling. Almost sounds like there's a performance cam in it. It'll sometimes idles high for a few seconds, then sputters & sometimes stalls. When I barely give it gas it sometimes sputters worse. If I give it lots of gas it sounds fine. It feels like it runs good out on the road & I'm getting 15 psi of boost. I recently had the sound ports covered & had the plenum ported. If the guy at the machine shop warped my case, will that result in the idling problem?