When you say adjusted and re adjusted... are you talking about the idle mixture screws at the front, and idle, just the basic stuff? This won't help, no matter how many times you do it.
You need the correct springs, rods, and jets for your carb.
edelbrock is not the best for performance, and to get dialed in. I'd suggest getting the kit from edelbrock that comes with the parts you need to get it running within range, or switching to a holley, with vac secondaries, correct power valve and jets....
The only Mustang I'd ever own is a Fender.
'68 333" Camaro
'14 5.0 Mustang