<VV> Low vacuum

[James Cuneo]

All, I have a 140 w/turbo that has only 15" vacuum at idle. Also, vacuum gauge has rapid 1" fluctuations. No vacuum leaks, checked every thing 3 times.Engine has 1k miles since rebuild including pistons, rings, rebuilt heads with intake valve stem seals.OTTO TB-20 cam. Cam degreed and triple checked at 4 degree advanced recommended setting. Would this be in the range of normal vacuum for this combination.How does this compare to stock 180?Engine will not not idle reliably/smoothly below 900 rpm. Have tried stock as well as a modified Rochester 2g carb.I am getting 23 mpg @ 60 mph with AFR of 14.2/1 with 2g carb.Other than idle, engine runs great.Any thoughts?Thanks,Jim Cuneonorcal 65 corsa