Hesitating expedition

[Busarider11]

I have a 97 expedition with 5.4. Starts and idles fine but under light load Boggs down like it's not getting fuel but I can let off gas and accelerate hard and it runs fine. Scanner gives one lean code and a p1150 code. I have replaced fuel filter, all coils, elbow boot behind intake, and checked fuel pump with pressure gage. Got 45 constantly. Any suggestions?

 

[Bedrck47]

HO2S-21 = DTCs P1151, P1152 and P1150
Possible causes:

Fuel system

Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Contaminated fuel injector(s)

Induction system

Air leaks after the MAF.
Vacuum leaks (vacuum lines and gaskets).
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated engine oil dipstick.

EGR System

Leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.

Base engine

Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.