Car shuts off when put in drive

Guys,
I was going to monkey around with the jets and metering rods on my 600cfm Edelbrock 1406 (as I stated in another post that I started here), but before I do that, right now I have a new problem that's severely affecting the use of the car (for what it's worth, I have an electric pump and a regulator (set at 4.5 lbs psi, an automatic trans, and it's a small block).

In a nutshell, when you crank the car, it runs and idles perfectly fine....BUT, when you put it into gear (reverse or drive), it stutters for a moment and then dies completely. If I 'nurse' it at a stop (brake and gas pedal at the same time), or put it in neutral, it stays running....and to keep it running, I have to feather the gas pedal and drop it in drive simultaneously, and it lurches into life, stumbles a bit (hence my question earlier about the metering rods), and then when it's on the open road, it runs seems to run fine.

Also, before it became this severe, I had noticed earlier when sitting at a stoplight that the carb would tend to "load up", i.e., start missing idle a little each time, hitching intermittently, until it would finally wind down and shut the car off if the light didn't turn green.

Now, as described above, it just shut off completely....I almost can't even back it out of the yard for it dying. Turning the idle screw up has no effect on the problem; and because it seems to run fine sitting still, I figure it's not the low speed idle circuit that's the issue here.

I do have the electric choke connected, but it's so warm down here this winter, I really don't need it hooked up...could this be causing the issue?

I also have the accelerator pump arm set to the longest stroke...should I set it back to the middle hole?

If I didn't need it to drive to work, I wouldn't fret with it or bother you guys...but right now, it's my only transportation to the job, and I need to figure this out asap.

Thanks,
Rob