Let me start off by giving some info on the carb. 5200 off of mid 70's pinto. I have adapted the carb to my 82 Chrysler Lebaron Convertible and it has run flawlessly for about two years. About a month ago out of the blue it will dump fuel into the intake thus running rich with black smoke. When it dies and you remove the breather it is still pulling fuel by a vacuum into the both barrels. Pulling the top off the carb breaks the suction. Letting it sit for a while sometimes you can start it right up like nothing ever happened. I have rebuilt this thing numerous times. Changed filters. Cleaned tank. I have a Holley carb manual and have checked to make sure I haven't mixed anything up. Any ideas?

About a month ago out of the blue it will dump fuel into the intake thus running rich with black smoke.

I had a similar issue, car never flooded but running rich and smoke = power valve was my problem