DopeSC400

Ok so when I start the car cold it idles at around 1000-1100 RPM. It progressively gets down to around 750 RPM. Once the car reaches operating temp, the RPMs plummet to around 200-150 RPM. The car never dies though. When I turn on the AC it raises the RPMs up a little higher. When the weather is warm and the RPMs plummet, the car begins to rumble and shake a little bit, like it wants to die, but like I said, it never ever dies. Also, my car is pretty loud. I have no resonators or mufflers. When I first start it my idle is super loud. But once it's warm and the RPMs drop, the idle becomes dead silent. This annoys me because I'm a douche and I love to bother people with my loud exhaust. Anyways, I'm thinking it's my TPS or I have a vacuum leak. Also, occasionally I will smell a strong scent of fuel when the car is warmed up. Doesn't always happen but when it does, it'll make you dizzy. Any suggestions??