Is gullibility related to low intelligence?

It is generally true that intelligent people learn quickly that trusting blindly is risky as well as foolish. Philosophically speaking, the need to trust in itself is a weakness, is it not? That we can't escape it is another matter, but the truly intelligent people take care to minimize the need.

There is street smart, and there is book smart. Street smart people are usually suspicious or people and situations, and are usually less gullible, while book smart people tend to be more trusting and thus more gullible.

skeptical/ untrusting people are the ones who are less likely to fall victim to gullibility, not intelligent people

No. People who are quite intelligent can be really gullible. Eapecially if they're really knowledgeable in one field and not so clever in another.

Some intelligent people trust people really easily, and some not so intelligent people wont trust people at all.

Intelligence and guillibility are two completely separate things. You can be clever and not so guillible in one area, and not clever and completely guillible in another.

Anyone can be guillible, no matter what their IQ.

It has nothing to do with intelligence, anyone can be gullible under the right circumstance. Including you and me.

Don't know for a fact, my opinion, gullibility is due to experience for the most part.