My toilet runs several times a day for 30 seconds or so and shuts off. Any suggestions?

20:1 says leaking flapper or corroded flapper seat or lift chain catches under flapper. Put some food coloring in the tank and look for coloration in the bowl. If you see color, start with a new flapper, take to old one to match. Make sure chain is not too long. Run you finger under the flapper and along the seat, if it is rough or appears corroded, they make DIY repair kits that work well.

Whenever I have toilet tank issues, I usually replace everything. The whole kits come in one package and are inexpensive. The kits come with step by step instructions to remove and replace. I'm not a handyman and I've become pretty good at toilet tank guts.