I interviewed for a job.Should I find another job or keep hanging on?

I interviewed for this job about 2 weeks ago. The man said Hey we're giving you a job offer. Cool job offer never comes the next week they sent me an email that said the position was filled. Then they send me an email that I got the job. My job offer to my background and my drug test and everything I do all of that and then they tell me they have to wait for my background to clear. I get an email that my background has cleared. I get another email that said the position has been filled, again. Then I get another email that says congratulations on your job offer, again. Should I keep hanging on for this job or just find another job?