I have 2000 Ford Taurus reading a code of PO174 running lean on bank 2 what could do this

Lean bank 1 and bank 2 , and throttle actuator system fault. Check reason for lean codes 1st, vacuum leak(s), air inlet boot and hoses, or low fuel pressure / clogged filter. Repair as needed then clear codes and recheck .

CODE PO174 - FUEL SYSTEM TOO LEAN CYLINDER BANK 2. POSSIBLE CAUSES LEAKING EGR GASKET OR LEAKING EGR VALVE DIAPHRAM. MAF SENSOR DIRTY .AIR LEAKS AFTER THE MAF SENSOR OR LEAKS IN THE PCV SYSTEM.EXHAUST LEAK BEFORE OR NEAR THE HO2S IS MOUNTED.WEAK FUEL PUMP,RESTRICTED FUEL INJECTORS.

P0174 FORD - Fuel Injection System Too Lean Bank 2

A PO174 LEAN CODE FOR BANK 2 IS THE CYLINDER BANK ON THE LEFT SIDE OF THE ENGINE
(THE CYLINDERS FACING THE FRONT OF YOUR CAR)
A LEAN FUEL CONDITION COULD EXIST IF THE ENGINE IS GETING
TO MUCH AIR AND/OR NOT GETING ENOUGH FUEL
THIS CAN CAUSE MISFIRE, ROUGH IDLE, AND HESITATION WHEN ACCELERATING
THIS COULD BE
A VACUME LEAK, A DIRTY AIRFLOW SENSOR,
A EGR VALVE NOT CLOSING LEAKING EXHAUST INTO THE INTAKE MANIFOLD
IF ITS NOT GETING ENOUGH FUEL THE FUEL PUMP COULD BE BAD, THE AIR FILTER COULD BE DIRTY
OR IT COULD BE DIRTY INJECTORS
ID TRY FUEL INJECTOR CLEANER AND A NEW AIR FILTER FIRST
THEN TRY CLEANING YOUR EGR VALVE. COPY THIS LINK TO YOUR BROWSER FOR
STEP BY STEP INSTRUCTIONS TO DO THIS.
www.ehow.com/how_4809842_clean-ford-taurus-egr-valve.html

IF THIS DONT DO IT I WOULD TAKE IT TO A MECHANIC TO HAVE THE OTHER THINGS CHECKED
HOPE THIS HELPS.

This code is usually caused by leaking intake manifold gasket on the front side. With the engine running, spray carb cleaner or ether on the gaskets. If the engine revs at all, you have a leaky gasket. If not, check for other vacuum leaks in anything attached to that side of the manifold. If you have more questions, please let me know.

This can be caused by a faulty mass air flow sensor

Leak on the intake, bad EGR valve that's not closing. Perhaps a bad O2 sensor, but probably not. The O2 sensor is what detects a rich/lean condition. But when they fail they usually give their own error codes.

How many miles are on the car? It could be one of three things.
1. Check vaccum lines running to the valve covers. The rubber nipple that connects to the valve cover sometimes gets a hole.
2. Could be 02 sensor depending if its lean on bank 1 or bank 2.
3. Also check DPFE hose's. Located on back of motor running from EGR valve exhuast tube.

O2 sensor faulty.

PO174 lean bank 2. Could have a O2 sensor problem but with no information on what's happening with the truck this is all I can give you.