Low RPM stumble

Recently my 360 has been having an issue at low Rpms. It idles fine at 1000, but it occasionally pops and surges when I quickly tap the gas. While cruising it hesitates and surges and it has also popped out the carb a few times up until about 2000rpms. Past that it runs just as strong as it ever has and has no hesitation or misfires. Fuel is getting to the carb and the accelerator pump is working great.

The things I've recently changed are an MSD ignition (made sure all grounds were good) but could I have low voltage to the box? New fuel lines and sender unit, new fuel filter. I also got a new distributor, and the timing set with vacuum advance not hooked up is about 13 initial and 34 total. Could I possibly need more initial timing? I also can't remember what the plug gaps are, but I know they aren't to MSD spec.

The engine is a 360, kb Pistons, stock stroke, lunati solid roller [email protected] and 578 lift, Holley 650w vacuum secondaries, eddy heads, headers and so on.