I smelled something that seemed 'electrical'. The knock was strange because it was only there at very light acceleration. If I let up on the gas or gave it a bit, the noise went away. After about a mile it did start to buck, but more like it was missing than anything else. That's when I noticed the smell. By the time I got the car pulled over the cabin had started to fill with smoke coming from the area of the PCM, but I think it was coming in through the firewall. I popped the rear decklid and I could see small flames between the front manifold and the firewall, right around the shift cables. Unfortunately I didn't have anything to throw on the flames to see if I could put them out, but then again it may not have done any good. I don't think we'll ever know what the cause was, there's little left of the car, it burnt right up to the windshield. All the windows broke from the heat, and the interior is completely gone, nothing left but the frames of the seats. If I'm able to get anything off it the only things I can think of that would be salvageable would be the front rims and tires, front springs, and the headlight motors.