Slight miss in motor..please help.

[Jefe]

I have a 68 Chevy, with a mild 350 in it. Just had heads machined and put together 1.94 & 1.50 stainless. New springs, new lifters, new aluminum intake, new points and condenser, plugs cap/rotor, new wires. When I am driving ( not all the time) but sometimes it will like "hiccup" it will actually miss real quik and return to normal, engine runs at about 190 degrees. I am thinking that it is a slight carb problem..(quadrajet). Checked the dwell and timing, both are perfect. New fuel pump too. Other than the miss every no and again, it runs really strong and smooth. Any ideas, anybody? Thanks again!