5.7L running too lean (very high NOx), won't pass state emissions

[Fast355]

If the 02 sensor was cooling off the engine would run rich, not lean. I would check your base timing and make sure it is set for TDC or 0*BTDC. Also check the base fuel pressure the engine is running at. These engines like to be in the 12-13 psi range even with a stock engine. Maybe as much as 14 psi with a higher flowing intake/exhaust setup. Finally check your injectors to make sure that you have the 61 lb/hr injectors, not the 46s or 55s from a 4.3 or 350. I would also suggest that dropping the coolant temp will help prevent the formation of NOx emissions. A 180*F thermostat will drop the numbers some as well.