Yea, drunks can be quite charming and very manipulative as well. He isn't really sober, he is sometimes but it's hit or miss. Most people lie with internet romances. Let it go. Otherwise you're headed for a lot of misery. I promise. Don't go anywhere near an alcoholic even one who SAYS he has been sober a while. But he HAS been drinking and it doesn't sound like he's told you about those times.
Read these posts, you'll find lots of lies by alcoholics that codependents bought much to their regret.