LS Engine Idling Issue

[ItDoRun]

Finally got my car started (after 8 years of building) but it won't idle at all. I have to feather the pedal to keep it running. Also noticed my volt meter on my New Vintage gauges is only showing 8 volts when running. Fan 1 comes on in the key on position. Let's start with the idling issue first though. I do know hat PSI programmed my ECM for the wrong style MAF. Would that be causing the issue? I talked to Gary at PSI this morning and he said the car would still run like it is.

2008 6.0L short block
LS3 heads
LS3 Intake
Custom cam/springs
Stock valve train

Ok, where do I start with the idling issue?