Engine coughing/sputter problem?

Need some help diagnosing possible cause for an issue I'm experiencing with my '82 KZ1100-D1

Bike starts fine, idles fine, rides fine at med/full throttle.
However, in 1st or 2nd gear at very low speeds (like 5 to 15mph in traffic) when I am only applying very light throttle, I will often get a cough/sputter from the engine.
It kind of sounds like a mini-backfire, or almost like the engine noise just skips a beat and then continues going. It does seem to afect power a little bit, but again I'm only going 5-15mph so it's not really a big deal. It goes away as soon as I increase throttle pressure.

I don't know the status of the carbs (clean or not) but I do know that the air filters are clean, the oil filter is new, and I'm pretty sure the fuel filter is new also.

This doesn't seem to happen at any other point in the power band.

Any ideas?

~Adam
'82 KZ1100-D1 Spectre

look for a vacum leak around the carb boots

what would that look like/how would I identify it?

You may have tiny particles of gunk or dirt that are clogging the jets.