Hey guys needs some help/advice or a direction to go in..im sure someone has had this issue before

5.7 ls motor that has been transplanted into a 62 impala..which was running fine till about a week ago

the car is idling at 2400rpm's and will not come down,
both side headers all tubes get glowing red so its running super lean on both banks.

i don't have access to a scanner so I have tried basic stuff but to no avail

checked for vac leaks..no visually cracked or loose hoses..sprayed intake hoses boosters etc with carb cleaner with no change

-map sensor replaced no changed
-iac valve replaced no change
-maf replaced no change
-throttle plate cleaned
-performed various idle air relearn procedures that ive seen posted with no change
-all grounds secure

I think I'm missing something very basic...help

 

Sorry that no has replied.
Running 2400 RPM and lean indicates a large amount of air is getting in, and if lean, likely bypassing the MAF.
Have you tried disconnecting the MAF?
Are you sure the throttle body (TB) is completely closed at idle?
Disconnect the MAF and pull of the boot to watch the TB at idle.

 

2400RPM is a pretty big air hole. Might check that
the MAP sensor didn't pop out the back. Also the PCV
boot by the TB is prone to crack with age.