Hi
Been there done that, still learning.

I've vacuum tested, smoke tested, pressure tested, leak down tested. pumped propane in & around, swapped multiple O2, Wide bands etc etc.
I've had intake leaks, exhaust leaks, water leaks. The list goes on.
Just plod through, it's all learning & knowledge.

I bought a CNC milling machine just to re angle the Edelbrock LT4 intake faces.

It runs Open Loop when cold just using PCM preset settings and tables.... check your computer water pump temp. It fails or cable break usually at like -45 so will be pig rich if it can't read it.
Black smoke is usually fuel
Blue smoke is generally oil ... could be valve seals ... or rings
White is water or coolant.

Once warm it _should_ go into Closed Loop & uses the O2 sensors to feedback any error on the fueling - Dataogger should show what state the motor is in.

Are throttle blades closed as much as possible so the IAC can control rpm. IAC should show on logger what IAC is SUPPOSED to be at but IAC could be stuck & not moving.

Once in CL you can read your Left & Right BLM & integrator values & can see how much the PCM is trying to achieve Stoich

If gauge is constant whilst running i'd worry about it later.
Removing the vacuum pipe to the regulator should see fuel pressure move ( I think it goes up to match the rise in intake pressure at wot . i can't recall but still be consistant

See Shoeboxes website shbox.com for anything LT1 related
See Steveo's site ecmhack.com for all Steveo's tuning info.

Good Luck

Mitch