Stumped and Frustrated with a Holley 670 Hesitation

Dont know if this will help or not but here is what I went through with my 770 Street Avenger. I bought mine used so I knew nothing about it. Put it on my 360 and it wouldnt run for crap. bought a rebuild kit for it and proceeded to take it apart only to find out the coating on the inside of the fuel bowls was literally peeling off in chuncks. Called Holley to try and order some parts only to find out Holley wanted that carb back and they sent me a brand new one. This probably wont help you but it might be worth taking a look at your fuel bowls. Food for thought.