If the PCV doesn't fix it for you, I would suggest checking everything that would make it run rich. Make sure the air bleeds are not blocked (they are the 4 very small passages on the front, just under the choke plate). I think the idle air bleeds are the outer 2. Make sure the floats don't have any gas in them, and are adjusted right. Make sure you have the correct gasket between the carb body and the metering block. Not a likely cause, but make sure it doesn't have some crazy sized jets in the front, (should be around a 76) because that could make it idle a little rich. I would definitely put another PV in it too, just to completely rule that out.