Said they wanted to buy what i was selling on craigslist with a company certified check. It was a text.

I got the same thing.  I told him (Robert Brown is what he gave as a name) that I would accept cash or payPal

I got text like above offering cashiers check and he needed name and address no PO box.
I said "Not likely".
Obvious scam

Texted back and forth for over a week.  They requested we remove the post from Craig's List, which we did.  They wanted an address and email for mailing a check.  We received a name (Halle), but not the name of his business.  Then there was a 'mistake' in issuing the check, which delayed the sale again.  This person is trouble and I recommend that you do not engage with them.

Complete scam funny group of people because it's more than one person working together