Help I've tried everything found one small vacuum leak one hose replace it and got it down to one code 0171 I cleaned the map sensor and their intake valve change plugs and wires had the timing chain replaced but still getting lean condition on Bank One and a for evaporator and na for second oxygen sensor can you be as simple as a bad oxygen sensor
I have to get the car inspected before it gets towed with this temporary plate and I needed to pass inspection I only have a simple code reader

 

Welcome to the forum

P0171 System too Lean (Bank 1)

4 cylinder engines only have Bank 1

How old are the O2 sensors?
They last 100k miles or 12 years and then go Lean when they run out of chemicals, ONLY sensor that has time/mile limit, like tires and brakes O2s just get used up
You have two, an upstream and downstream O2

2.5l was only used in Ranger from 1998 to 2001 so we are well passed the 12 year mark, in fact should be going onto the 3 set even if its a 2001 model year

If you are still getting P0171 after new O2s, need to drive at least 50miles with new sensors to clear code if thats possible
It may self clear if you hold RPMs at 2,000 or so for a few minutes

To check if there is a vacuum leak
Warm up engine, let it idle
Unplug the 2 wire connector on IAC valve
RPMs should drop, engine may even stall, either is good, it mans NO vacuum leaks
If RPMs do not drop then you do still have an air leak, leave IAC Valve unplugged and start pulling off vacuum hoses and use finger to plug that port on intake, start with PCV Valve hose and Power Brake Booster hose
When RPMs drop you found the leaking device

Other reasons for P0171 besides vacuum leaks and O2s
Clogged exhaust, you can use a vacuum gauge to test for this
Clogged fuel filter, reduces fuel pressure, fuel filter should be changed every 5 years or so
Fuel pump, same reason, computer expects 50-60psi pressure, if its lower then computer sets lean code
Dirty MAF sensor, easy to clean these

 

I've got a 99 2.5 with the P0171. Most sites say if all else fails it's the PCM.. It can be fuel filter, pump, maf, air filter, vaccum leaks, injectors, and an array of EGR related parts?

What I've done:
-Cleaned MAF with rubbing alcohol
-Start fluid test manifold and all hoses; no idle change
-Unplugged IAC while warm; it went low rpm and eventually stalled
-Unplugged MAF while warm; stalls
-OBD2 reset and cycle; p0171 triggering snapshot below
Fuel Sys 1 CL
Fuel Sys 2 N/A
Calc Load 38.4%
ECT 190F
STFT 0.0%
LTFT 12.5%
RPM 2802
Veh Speed 71MPH

All DTC monitors done except evap which eventually caused that snapshot while on interstate dong 71

EXTRA RELATED QUESTION: Does this code clear without a new monitor cycle if problem is fixed?