Alright so here's the background:
I have a 1973 ford f-100 with a 390, Edelbrock performer intake and an Edelbrock 1406 600cfm carb on it. I just installed the carb and got the vacuum and air mixture screws all adjusted in (for the most part). It's idealing a little high but nothing to serious. Also has a c-6 tranny

The problem is when I try and throw the truck into gear, it stumbles and immediately dies. I can not figure out what's going on. Any suggestions will help. Haha just want to get my truck driving again

 

If the mixture screws are almost all the way in, it may be running quite lean.

I havn't much experience with auto tranny's, but I seem to recall you adjust your idle mixture with the car in Drive and someone holding the brake on, or use the parking brake if you trust it.

Other than that, alternate reducing your idle with the throttle stop screw and peaking it back up with the mixture screws until the idle is where you want it. You may be running too much on the Transition slots (if there are any on your carb).

Also check your secondary butterflies arn't open too much. Just enough they won't stick in the bores. Then do the primary mixture adjustment as above.

And double check everything. Make sure your vacuum hoses, PCV, etc., are connected up. Sometimes a person misses something when swapping parts.

Anyway, just guesses on my part, but things I'd try if I had the problem.

 

Speaking of missing things, did you install the pipe plug in the back of the throttle body?
Is the intake a fresh install, or has it been on there a while? Could have slipped the gasket on you if it's a fresh install, as even in aluminum, they ain't light.
Couple of edelbrock carb specific checks, fuel dripping into the top of the primaries while running? Pretty common thing, if the metering rods are not seated correctly or the floats are a bit high. So common, I've seen it happen with one straight out of the box......
Carb spacer used? If so, is it a 4 hole? Edelbrock carbs don't seem to like open spacers for some reason, even on an open plenum single plane intake. Most likely has to do with the vacuum runners for the metering rod plungers and "Step-up" springs having been designed to work best on a 4 hole intake/spacer.