So i got my new long tubes and ory pipe from DNA motoring and put them in bout a week and a half ago...ran fine with no problems untill a few days ago it started throwing the codes P1153 (H02S insufficient switching bank 2 sensor 1), P0154 (H02S no activity Bank 2 sens 1). P0174 (System too lean bank 2). I replaced bank 2 front sensor with a stock ac delco 02 and codes came right back. Fuel pressure is 50-60 psi. checked all vaccum hoses and they seem to be fine, i cant find a vaccum leak anywhere. Maybe the mass airflow sensor is bad? dont know how to really check it without a scan tool...do you guys have any idea wats wrong with her?? thanks for any input