383 dual quads lean at idle and cruise

Moparpuller said

Put the intake back on with 1 inch open spacers. Went and drove it after setting everything. Same thing. Above 28-3000 everything is happy. Under that and it starts getting lean on the left side and missing

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Ever consider You've got a low-speed ignition misfire? If there's a carbon track in the cap near 1-3-5-or7, and the rotor tip is in proximity moreso closer to base timing, it could be jumping past the tower post. Misfire shows up lean, lots of unburned fuel, may pop &/or act like it's flooding. Is it an erratic misfire?
Otherwise, how did the intake gaskets appear? It does sound like a Dr.side vacuum leak, or plugged idle circuit, but these are some other things to check out.
Peace.