<VV> Fuel/Driveability Problem

[Bill H.]

                                                                                      B"H
Hi all, I really could use some help!  Up until about two weeks ago, my car ('66 Monza, PG, 110 A/C) ran like a new car.  Smooth, quiet, peppy.  At that time I filled my tank with Hess Premium and the next day, she started to run horribly after warmup.  Stalling, bad hesitation, shaky idle in Drive.
Assuming it was bad gas (water?), I drove until the tank was empty, then filled up with Mobil Premium. After almost a week, the problem seems to get worse.  When she's cold, she drives fine.  Smooth, powerful.  As soon as the engine warms up (and chokes open), it shakes, stalls, and hesitates.
I checked the carbs and noticed gas dripping from below the venturi cluster on both carbs.  I don't know if this is normal or not, but I took the air horn off one side and checked the float and the float seat and valve.  Everything looks fine, the needle slides easily in the seat.  I also checked the float level when the air horn is right side up and the floats are hanging down.  It was within specs (1.5 inches from the carb gasket).
The way the poor car runs now, she's not even safe, because she stalls whenever I take my foot off the gas.  If I step hard on the accelerator, she goes.  It seems to be at idle and just off idle that she's running badly.
Timing is OK, I've tried adjusting the idle mixture screws but nothing has helped so far.
If the problem is the floats, I'm not sure whether "raising the float" means less drop when the air horn is rightside up?  The floats themselves look good.  These are good quality rebuilt carbs that I got in 2012.
Can anyone help?  
Thanks everyone and best regards...Bill Hershkowitz