I have a 1994 Mustang GT, its only modifications are a cold air intake, catless x pipe, and a catback. The car at idle sounds lopey and choppy as if it was cammed but I don't believe it is. I smoke tested it through the hose that connects to the PVC valve and nothing. I smoke tested the exhaust and it only escaped from behind the muffler. Drove the car today after it sat for a few months while I worked on it and it idled less aggressively and the engine feels very hot making the hood hot. Any ideas what could be causing this?