i hear some cel cause by replace a lighter fly wheel or some of them cause by MAF by replacing a intake my qustion is can tuning the ecu like utec, AP, reflash....... fix the cel propblem?
also if the car need to go to emission, does it need to cel free ( no cel) b4 i take it to emission ( state IL)

 

you can turn the CEL fix on but it wont fix the cause

it reads misfire if you have too light of a flywheel / crank pulley combo

i dunno about IL emissions but california yes

 

first off to pass emissions test the CEL can not be on if it is they fail you right away
if your getting MAF faults its probably the oil from your aftermarket airfilter getting on the sensor or excessive turbulance in the intake pipe, only cobb intakes cure the turbulance problem, but normally the turbulance only causes driveability issues (flat spot in throttle) not CEL codes.