As I'm accelerating up in the entrance ramp to the parkway, i hear a not too loud pop from the exhaust, then the car starts decelerating. I cannot longer accelerate, and car is running really rough. I pull over to the side. A big cloud of smoke comes from underneath the car. I try to start the car, the car doesn't start most of the time (it cranks fine) when it starts it runs very rough, if i give it gas, it doesn't respond very well, and as i struggle to get the rpm's up, smoke and flames come out of the exhaust. When the tow car moved the car, the grass underneath it was burnt. It sounds like the cat. What do you think?