got a stock 305 camaro today I was coming home and about 10 min from the house I was running about 50mph and it started running rough. Sounded like the catalytic converter. I got home and popped the hood and there was a little smoke coming from the passenger side firewall by the valve cover (no valve covers are not leaking). I checked all my plug wires on the dist. and they were on good. There is plenty of exhaust coming out of the tailpipes. If it doesn't seem like the cat what does it seem like. Thanks

 

If the cat was beginning to get plugged, you'd notice the engine running out of breath at ever lower rpm. If it happily pulled 4500 in first gear, the day before your trouble started, then it probably isn't the cat.

 

I did not think it was the cat but wanted to make sure. Any idea on what else it could be? Still waiting on it to cool so I haven't checked the plug wires at the engine.

 

check vacuum lines as well - a vacuum leak can cause a rough running condition

 

thanks, still waiting for it to cool but will check that along with the plug wires.