major carb problem please help

[HemiChallenger]

I can't figure out what the f$!k is wrong with the carb on my truck. Once I adjusted the valves the thing had a bad bad stumble, the accelrator pumps were way to heavy and sprayed fuel as soon as you tapped or bumped the throttle. So I tightened up the springs, and still to no avail when the accellrators kicked in bad bad bad stumble. So I adjusted the floats, same problem only worse now with the floats adjusted properly. The thing has backfired about 50 times now and wont even fucking run, I adjsuted the floats all the way down and still to much fuel and it just dies out weather I have the fuel pump turned on or off (I have a manual switch). WTF is wrong I almsot killed the truck and myself I was so pissed off, any input would be appreciated. Oh and this is a NEW holley 750 double pumper, thing ran fine when I bought it not now.