Yes when gurgling is going on then you have a problem with the main sewer for sure and as it drains it will gurgle when there is a major block or separation , Good luck and use the information i have given you and print it out if you want and read over it again so you have a good understanding . thank you for Choosing Just Answer.
on the first floor of the house go run the bath tub or shower , and flush all toilet , then go run the sinks that have been giving you the problems. Depending on how your house's plumbing is ran all depends on how the problem will accrue . If everything in the hole house is working fine except just a couple of sinks then come back to me and I will explain some other things , but make sure you run everything for a while not just a couple of seconds , more like a couple of minutes with everything on .