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Your carb sounds like it needs a few things checked Joe. From what you have described I would check the power valve seating. Make sure you have one on the primary side and that the gasket is seated properly. Power valve itself may be defective also. A 6.5 is fine for street/strip unless your engine vacuum is way low, say...below 9 or 10 inches. Then a 3.5 or 4.0 may be needed for a power valve. Secondly, when you received the carb, it may have been jetted very rich out of the box. I will assume all your rejetting, to get a good A/F ratio, was done on the secondary jets only(?). If so, that would leave the primaries still in a rich/cruise mode. I would suggest getting an A/F sniffer up the pipe and a chassis dyno under the wheels. Run the motor to 3000 rpm under a light load and check the A/F ratio. Should be 13.5 - 14.0 at cruise. After you have dialed in the primaries, do a full pull, watching that the new A/F ratio doesn't lean out the motor. You may need to richen up the secondaries for a final A/F ratio of 12.5 - 13.0. This is all based on speculation.

Finally, make sure that the throttle blades have not opened so far as to expose the transition slot too far while you were adjusting the idle speed. If you are farther than .040" exposed on the slot, you will get a very rich idle mix that won't clear up until you are on the primary jets.