Geodude, I would look toward ignition timing. You mention that the "cam timing is good" but then you say that might be your problem. Which is it?? How do you know it's good?? I doubt that's your problem, it would have to be way more than a tooth off to run that bad. But ignition timing is definitely a possibility. Start over with the timing, make sure it's advanced enough, and check to see that it's hooked up right. Did you mess with the carb at all? Is it the same one you used before, and how did it run before? And Docone31, no offense meant, and I think someone is hinting at this in another way, but valve covers have nothing at all to do with how an engine runs. Think about it, it makes no sense.