Whelp here goes this one...
What year is your car?
Intense could have loaded the incorrect year MAF tables into it...since you have a Aeroforce...switch it to the LTFT's (Long Term Fuel Trims)...when idling or coasting off the throttle if your fuel trims peg at +16.4 then you have either...
A) An actual vacuum leak...which is what the code P0171 is for...
or..
B) You have to either have a local retune your car or ship it back to intense and have them flash the correct MAF tables in your PCM (Example: '97-'98 cars have the same MAF tables...but then '99-'03 are different)
