Help with E38 Cold Idle

[Phillipm]

Engine is a stock 2009 LY6 swapped into a 1978 Blazer.

I've tuned the MAF and when I went to do the VVE it had zeros everywhere. Which makes sense. It's got a set of headers and that's it.

Trouble is during cold idle warm up if I've got the MAF off it idles awesome. Nice and smooth. If I turn the MAF back on it cold idles terrible. Shakes and hunts and the MAP Kpa is bouncing around.

Any help would be appreciated!