Here is Fords opinion:
P0174 - System to Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
(Possible Causes for DTC P0171 For lean and rich DTCs
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Air leaks after the MAF.
Improperly seated engine oil dipstick.
Stuck EGR valve.
Leaking diaphragm or EVR.
Exhaust leaks before or near the HO2Ss.
P0301 through P0310 - Misfire Detection Monitor The misfire detection monitor is designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. Ignition system
Running out of fuel
EVAP canister purge valve
Evaporative emission system
The MIL will blink once per second when a misfire is detected severe enough to cause catalyst damage. If the MIL is on steady state, due to a misfire, this will indicate the threshold for emissions was exceeded and cause the vehicle to fail an inspection and maintenance tailpipe test.
'00 XLT 3.0 Exted cab
Mods: Roush hood & cai, ASP pwr pulley, hot wtr bypass, 180 therm, e-fan, Gibson exh., 4.10 l/s, FabTech lift, kyb's, bii sway bar. 31x10.50 Yokahama ATs, Panther rims, light bar, SS grille, 03 stang buckets, explorer console, hurst shifter