Is it normal for my almost 3 year old to snore loud and sometimes stop breathing for a few secs. Does not have cold and we have a humidifier running?

Uncommon & progresiv. If a kid is snoring at 3 it is likely to progress to a point where it causes sleep apnea even if it is not present now. T&a mass grows faster than the kid until ~8y. If your kid is grumpy, dozes a lot during the day & the pauses you mention last >10 sec, you have a problem now. Record the snoring pattern & seek out a consultation with an ent. The humidifier is unlikely to help.
Sounds like OSA. Sounds like obstructive sleep apnea. A very common problem in children, particularly those with large tonsils and adenoids. Causes poor sleep quality and over time can affect heart, lungs, behavior, attention in school. Get this checked by your pediatrician or ent. Often, removing the tonsils and adenoids is curative.