Stock mechanical pump... I am going to change it out, but will that affect the idle, or just wide open throttle? It says I am running around 7 lbs of fuel... and I can't think that would be correct, unless I have a high volume... I bought it over 10 years ago, and swapped it with a Holley Hi-volume pump, which made no difference in the way it run on my 396 back in 2000 or before... It was a Carter... but I don't remember what part # or if it was stock or High Performance... I put it back on when I fired my engine for the first time, because I was getting no fuel, and my Holley took a dump, so I just put on the one I had on the shelf to get it running... but with a 600 or 750 Edelbrock I don't have the erratic vacuum, or an eratic idle... This thing really idles like crap with this carb on it...
Pull the carb and start over just like mention above with the transfer slots for the throttle blades and the float level these are extremely important... While you got the carb off clean the small holes air bleeds and in the bowl with carb cleaner and tighten up all screws... Then just set all 4-mixture screws at 1.5-2 turns out.. Make sure that after it fires you adjust the mixture screws back in one at a time until you feel the slightest stumble or rpm drop in the motor, then back it back out 1/16 and do the same to the others... I like to concentrate on the fronts first (primaries) then the rears (secondaries) and these will be very little adjustments 1/16 at a time once you get it to idle right.. The other thing is if your coil is acting up it will give you the same problem at idle like it did with me for 4-weeks until the coil just quit working..
Ignition first, coil, cap, rotor, wires, and plugs.
Fuel second, pressure should be fine, jets, air bleeds, power valve, accelerator pumps, float level and air fuel ration (mixture screws).
It sounds like you have the transfer slots off and float levels plus the mixture screws may be to far out. Its probably got fouled plugs in it now and it will be hard to tune with fouled plugs.