Mixture seems to lean out while cruising but not acceleration/decel and idle

[crazypete]

yeah, it seemed to idle at a steady 19 hg's of vacuum before, then I found a serious defect with the carb (secondary plates were jammed shut by the primary throttle linkage. Even at wot, max secondary motion was at most 30 degrees). I sent my 570 back and they sent me a "flowtested" 670 instead. Now the idle seems lumpy. I'm not using any of the carb ports at all. My pcv is using the sealed 91 system without pcv valve since the edelbrock performer does not have a pcv passage at the back of the intake. I have the valve cover oil filler stem air tube hooked to the air cleaner dish underside. That should create some minor airflow through the tube. Do carbs have internal leaks? If I didnt know any better, I'd say this carb has an internal leak