I have a 97 GS-R Manual transmission. It's all stock except for a racing clutch and adjustible suspension. At a light the other day i heard a pop in my engine when i started out and now my car's really sluggish. There may be a faint smell when i'm driving... but it's not really that noticeable so i can't be sure if it's my car or my town. I just got oil and coolant all filled up. Any ideas?