hi guys maybe you can help me out?
i have a 77 nova with a 305 4v automatic, it had a exhaust system that went from single into the muffler and out dual to each side of the car. Up until i changed out the exhaust to dual headers it seemed to run fine, now it sounds like it's missing on a cylinder, but when i checked the headers for heat all were equal. I check the plugs and all are nice and light brown, i also checked the timing which is ok. at idle it sort of chugs by sound only, meaning that you don't feel it when you are sitting in the car. I have checked all the plug wires as well. It doesn't or should i say hasn't back fired at all, just has a very annoying way of sounding, sort of like a school bus that runs on gas sort of chugging.
anyone got any ideas before i start pulling it apart?

thanks
IMnuts