01 V6 3.8 Bad Misfire

[Cotton Dozier]

I have a 2001 Base 3.8l automatic and it was running good all day one day, until I went to pull away from a stop sign and barely got on it. Next thing I know is my stang made an awful noise, then was completely weak. It felt like it lost all horsepower and began to hiss real loud from the back passenger side of the motor. I'm guessing it is coming from somewhere in my exhaust system. The car keeps acting like it wants to sputter out and when It's parked it idles very rough, and it sounds terrible when I rev it up. I had checked the fuel filter first it was fine, then I replaced all plugs, plug wires, and coil pack, still ran the same. So I had a buddy come and run the codes with his OBDII reader. The only codes it showed was something with the EGR valve, Random misfire on Cylinder #2, and the Throttle position sensor. What all should I do to get my ole car back running again???? Oh and by the way when I bought the car it already had the exhaust tip ripped off and the muffler was pretty much dragging and I had caught the muffler on stuff a lot before I ever got it rigged to where it wouldn't drag anymore. So I think my exhaust could be coming apart somewhere. Could a leak in my exhaust cause the rough idle and loss of horsepower???