Why does my car sound like a mustang?
 

Hey guys, first I need to admit I didn't try searching the forums but I gave google a shot. Very busy week and my car is making it worse...

It's supercharged and has been having some kind of aspiration problem on and off for a while. I'm assuming it runs rich because it spits black stuff out the exhaust sometimes at idle when the revs get wonky. The other day The exhaust started sounded really choppy and raspy like the mustangs here in Texas sound like. I drove it around for a couple days and it just kept feeling heavier and slower. I think it's revving higher than usual too, not quite sure.

The check engine light finally came on and I just feel the car dying so I stopped driving. It's the weekend so everything is closed and I'm a little desperate/worried. Does anybody have any idea what's going on? I'm hoping it's just a matter of cleaning but I'm pretty inept when it comes to cars nor do I have very many tools. Please help :( Thank you all in advance

Use an OBD scan tool to see what triggered the idiot light and go from there.

My quick guess would be fouled plugs and/or misfires, hence the black "stuff" and the CEL.