Engine running like crap

[4x4exploder88]

Like the title says, the motor in my 92 explorer is running like crap, low power, and extremely bad mileage, sometimes I have to lightly push on the gas when i first start it up to keep it running.

In the past 2 weeks, I have changed plugs, wires, air filter, and fuel filter.

I have scanned for trouble codes. Here is what I got:

Performing a KOEO test, I got the 111 pass code, and when it starting giving me memory codes, I got 157 - Mass airflow sensor fault - low voltage.

Doing the KOER test I got 2 codes

172 - HEGO sensor fault lean condition

*EDIT* A spark plug wire was left unplugged!!! Retested and code 172 is no longer existant. Still feel like it has alack of power though.

And I got 536, which is because I didn't push the brake pedal and it didn't activate the on/off circuit.

So, does this mean I need a need an oxygen sensor? Could this be the reason I have been getting about 10 miles a gallon and have lack of power?

 

[95LimtedExplorer]

Replace the mass airflow sensor, its part of the air intake tube, it mounts onto the air filter and has a wire harness going to it.