I have a 66 mustang with a 200 straight 6. I was just wondering how the idle is suppose to be. Mine is rough. Not too much that it is un drivable, but enough to aggravate you. New plugs, new wires, new Petronics, new carburetor, actually this is the fourth carburetor that I have tried. Timing is good, no vacuum leaks that I can find. Any ideas or suggestions that I can do?