Toyota Repair: 99 toy tac 3.4 5sp po171, mass airflow meter, air fuel ratio

Question
light comes on every 3-4 wks...I erase it and then it comes back I already replaced both O2s I have a KN aircharger kit and unknown header the motor got new head gaskets about 15000 miles ago What other DIY tests can I do?
thx 4 your time  

Answer
This code is caused by a lean air/fuel ratio, the problem is the mass airflow meter(MAF)it's located in the intake air tube just behind the air filter housing, replace it and it may be a good idea to remove the K/N system because the filter is oil saturated and causes the MAF to accumulate dirt because of the oil deposits that get on to the platinum sensor wires, you can leave the system on but be prepared to clean the MAF with electronic cleaner every few thousand miles, you can try cleaning the existing one and it may last a few thousand miles, use electronic contact cleaner only, spray it inside the opening of the sensor to clean the sensor wires, let it air dry or use low pressure air from a can, give it a try and it should last for a while.