Posted this problem several times, without any significant help. I have a new Edelbrock 1404 (500 CFM) carb on my 302. It runs extremly RICH, and I cannot lean it out. I have played with the mixture screws, and while they have an effect on idle quality, it is always too rich, and the carb loads up. On acceleration, or cruise it is fine. If I let up on the gas for a second or two, as if to coast, or shifting gears( 4 Speed) when i step on the gas to resume, it stumbles for a split second as if the carb is loaded up. Vacuum is about 19 " at idle and is steady. I don't have a timing light, but it seems O.K. is this an issue at idle?? Electricals seem fine. I appreciate previous responses, none were helpfull. Any carb experts?? I need help with the rich idle problem.