First off, retorque your intake manifold, then retorque your carb. Not overtorque, correct torque.
Start it and see if it's better. Were either of these carbs "known good" or were they questionable? Did you use a good base gasket?
If the carb should be OK then get some carburetor cleaner or even some compressed air and start shooing it in bursts at any spot where there could be a vacuum leak on the carburetor, carb base gasket, or intake manifold.
Highly unlikely that you got 2 broken carburetors, but I suppose it could happen.