Garbage disposal gurgles once after draining + one other sink in house as well

Hey guys, question here. I have a double sink in my kitchen. The side with the garbage disposal will gurgle when it is done draining, once. The other side, which has a straight shot to the p-trap, also gurgles once, but usually not as loudly. The dishwasher drains into the garbage disposal side, so that does the same thing. Just after the P-Trap under the sink there is a Studor Vent. I had one of those cheap black vent caps on it, but that actually made the water drain slower in addition to the gurgling. I also have one other sink in the house that does the once-drained gurgle. But it is on the second floor, attached to another piece of pipe under the house that hits long before the sink split. And get this: the other sink in that bathroom never gurgles. Neither have Vent. There is a Y connector where two large pipes meet under the house. Straight back is that bathroom pipe, to the right is the kitchen sink pipe. That connector has clogged twice in the past 2 year and I can easily clear it with an auger, but I am wondering if an airflow issue is making solids sit there or something.