Service Engine light on

[01qx4]

My engine light in my 2001 QX4 is on and I am getting the following engine codes; P0171, P0174, and sometimes P0175. I know some people have cleaned MAF sensors and cleared these codes. But I have not had any luck cleaning mine. I even replaced my MAF sensor, but my truck smoked (black smoke) and would not idle at all. Maybe I damaged the sensor or maybe it was not any good from the start ( i orderd it online). With the old MAF sensor back on my truck besides the codes, skips a little at idle and if I "mash the gas to the floor" it skip and flutters a lot!!! Any ideas anyone??? I cannot get it inspected.

[02pathy]

simple, i think u need a tune up, and spraying the maf sensor with air intake cleaner (not carb cleaner) might be part of it if the filament is black (the little chrome thing in the maf), the fact that u r getting those codes means to me that ur car is not burning the fuel properly, i would check the spark plug, fuel filter and use preminum gas, and maybe a gas additive, maybe u might want to do a fuel injector clean out at the dealer(reason y i say dealer is because some parts r very sensitive to cleaning, like the throttle body that might need the idle air relearn procedure)

ps unburned gas in ur catalytic is not good at all, will burn them out

hope that helps