I have a 350 bored .030 over with intake, mild cam, headers, exaust, holley carb, ported and polished 2.02 heads, 10.1 compression, msd ignition, roller rockers, and everything machined and balanced. There are no problems starting the car, but if you try to move it shudders terribly and if you let off, it will idle down and stall. If you give it a little more gas, it will backfire from carb if to lean, and from exaust if to rich, and instantly die either way. I just readjusted the rockers but I know they are done correctly. People are telling me either valves or idle mixture screws but I have played with both to much for them to never be right. Anybody have any ideas?