What if;
one or more intake valves are not closing? When the piston comes back up on the compression stroke, she will pump some air back up into the intake. If that air or even just the signal makes up to the carb and past the throttle valves, the boosters will sense it and they don't care which way the air goes thru them, so they will drip.
By the time your engine does this, the tuner has usually fudged just about everything into a horrible state of tune, trying to figure it out.
So while I agree with everyone that mentions the floatvalve/floats; I just want to mention that there are other possibilities; and with a solid-lifter engine, I usually start with a valve adjustment and a compression test, and finally verifying the Idle-Timing.
In the case of the not-sealing floatvalve, I usually just pinch the rubber fuel line off. As the fuel level drops, it will run better and better , even speeding up for awhile. But then, as it begins to run out of fuel, it will slow down and eventually sputter to a standstill.