[regamble]

Start with the hesitation. Your squirters sound about right for setups like this I've seen, but what accelerator pump cam are you using and what position? An 830 is a pretty big set of holes to draw vacuum through effectively and maintain a decent draw on the idle circuit, so what motor is this on? I know an 830 on almost anything under 450hp is going to have some issues. My son's Ranchero with a 425hp 429SCJ runs it's absolute best with an 800cfm. By the time you get enough fuel going into the carburetor to balance out the huge venturi, it's running rich.

The backfire. I'm going to use a different term here called "off fire" and that is when a cylinder fires with the intake valve open but not the same as detonation or pre-ignition. A backfire through the carb can only be caused by combustion with an intake valve open. That said, if it's running extremely lean or extremely rich at idle, when you open the throttle it can cause a cylinder to "off fire" causing a pop through the carb. Basically, in each of the two scenarios, if it's very lean each cylinder is going to be much hotter than normal and when the squirters flood the runners with fuel it can ignite the moment the intake valve opens causing it to "off fire" and POP. In the other scenario, if it's very rich, it could be causing a near wet foul and when the excessive air hits the runners it dry's the excessive fuel causing a cylinder to fire as soon as the fuel/air ratio hits optimum.

Lastly, one thing I've encountered is incorrect vacuum advance timing. If the VA signal is premature or delayed it can cause both of the issues you are finding here. It may be, once again, incorrect carburetor, or a number of other things. Most Holley's have a screw on the secondary butterflies that allow you to open them just enough to remove vacuum from the VA and still idle on the idle circuit. If that setting is wrong it will cause VA issues, hesitation, and secondary jumps or inconsitencies.

Holley has a phenominal tech help line. Email them your application and problems and they will email you back with good information. Be as specific as possible. And no, you don't need to have a new carb to ask. I have used their help line on a number of 30+ year old carbs and they're always helpful and courteous.

Anyway, kind of long winded, but I hope this helps.
Rob