Unless I've read this post wrong (ignore me if I have)
You don't need to disconnect the battery to pull the MAF connector off. Don't clean the MAF with WD40, it'll make it worse. Use MAF cleaner.
You can also just pull the middle bit out of the MAF housing to clean it, saves taking the whole thing off.
If it smokes first thing in the morning, unplugging the MAF probably won't change it. It runs the default map at startup anyway. But try cleaning it.
I'm going to say you've got a leaky injector.
But that's just my opinion.
Cheers
Mike