318 Motor, please help

Hello, I just joined this forum because i'm at my wits end and i'm hoping you guys can help me. I have a 1969 318 LA engine with a 904 automatic transmission. i just put new points in the ignition, brand new plugs and wires and brand new coil. it has a Holley 650cfm 4bbl carb. I have a 4.5 power valve installed because the vacuum reading in gear is 10. (at idle in park its at 20). The motor fires right up and idles great. i let it get to operating temp (190) and as soon as i put it in drive it wants to stall out....if i play with the gas pedal a bit it will come up to a steady idle after a few seconds. if i stab the gas it falls on it's face and most times will pop from the carb and stall. so i have to carefully play with the gas pedal to get rolling without stalling. once its rolling it drives nice and smooth. what am i missing???