car is stalling out in gear

i thought my problem was fixed but now it is doing the same thing all over again. the car when i first start driving it is ok i can leave it in drive and it is fine it wont idle low or stall. but after i get off the freeway no matter how many times i park it and let it cool down it just will not stay alive in gear. i am forced to throw it into neutral at every stop because if i leave it in drive it stalls out. the carb has been rebuilt, i have changed the manifold gasket because i had a vacuum leak and the cap and rotor have been changed and it is ok as long as i stay away from stoplights or stop signs but as soon as i get to one the car wants to die. i am stumped i am thinking its just time for a new carburetor because no matter what we with it, it never stays in adjustment. any ideas on what it could be? heres my build:

S.B. 360
ported x heads
Comp 284XE cam
Holley 670 Street avenger (6 years old)
MSD ignition everything
Edelbrock air gap intake
TTI headers

thanks