-It seems like my exhaust has been slowly getting louder... maybe I'm just imagining things
-I was slowing down for a red light a few weeks ago, not braking very hard, and as I downshifted into 2nd, I heard a distinct loud pop that seems to come from the front of the car. Before, during, and after the fact, the car drove perfectly fine. My brakes are fine. No issues with the clutch or shifting. Maybe a small exhaust leak causing a backfire?
-I have a rough idle, especially when cold. Cleaning the throttle body helped a little bit but only temporarily.
-When the engine is cold it revs unevenly. That is, there is hesitation and in neutral at a steady throttle the revs oscillate within about 100rpm
-Tonight it cranked over for a good five seconds before starting. It was warm too; sat for maybe half an hour after I'd driven it.
-Over the past year or so my mileage has been dropping. From an average of 27 or so I'd gone down to 25. Last tank was 22mpg. Just for reference, last year when I autocrossed I got 21mpg, so 22 is pretty bad when I'm not racing.
edit: changed plugs and wires less than a month ago and it didn't seem to have much of an effect. Friend suggested I go back and double-check the gap so I'll do that