Protokiller

I have a 98 V6 dual exhaust with 278,000 miles on her (Built Ford tough, this baby is not found on road dead!). I need to smog my car and I have code p0174.

Some things I have tried: disconnecting battery, code keeps coming up.
Cleaning the MAF. Putting fuel injector cleaner in the tank. Checking for leaks with the naked eye.

I have had my fuel filter changed last year so I doubt it is that..

P0174 means the car is running lean on Bank 2, something that I find curious as bank 1 seems fine.

Any suggestions on what to try next are welcome.

BabyGT

Change plugs, possibly wires, and coil pack as well. But start with plugs.

PNYXPRESS

check your exhaust for a leak before the 02 sensors or poss a bad o2 sensor

Protokiller

I am leaning with PNYXPRESS as I pulled all the spark plugs on bank number 2 and tested to make sure they all sparked and were gapped correctly.

An o2 sensor would make sense now that I did much research on how they work and even watched a video of someone testing a faulty one and the voltage it was giving out would trigger a lean condition all the time.

I have checked for vacuum leaks, lose hoses, and even did a poor mans way of smoke testing the car to no avail.

With as many miles as the car has it would make sense that an o2 sensor could be bad.