So today after taking my car out for a 20 minute ride full of quick accelerating and brake down the back roads, i went home and parked for about an hour, then I came back to my car and when i started it back up it was idling under 500 rpm and it was a really rough idle. When I had this problem back in april I replaced the spark plugs and that seemed to fix the problem,now it is late september and I feel like im not actually fixing the problem, maybe im just covering it up slightly. I'm really not sure what is going on with it and would like some input. Thanks!

 

Try SeaFoam. Post the results.