injection issues? cutout

[Dillon79scotts]

So i have a 2000 chevy 5.3l, swapped into my 79 chevy 4x4.

runs about 50-60 psi depending on the vacuum of the engine.

I just recently started having a missfire, not bad enough to throw the check engine light on.

I was thinking it may be because i have a exhaust leak before the o2 sensor for some time now and it may have fouled a plug.
NOT THE CASE. i pulled both sides out and they all looked new still ( only month old AC delco's)
ONE DTC CODE I AM GETTING IS IDLE AIR CIRCUIT HIGHER THAN SET VALUE (or something along those lines)

I swapped coils with known good set.
i also just did injectors from another intake (same part number of injector)
and still no change.
tested them all with a noid light. every injector plug-in lights it up.

but are they firing on time?
could this even be a injector ground wire issue?

cam position sensor?
crank position sensor?
knock sensor? ( these are just my assumptions..)

if i can get some help with this and get my LS back on the road i would be very happy.

appreciate any help.
thanks