I have a 2005 ford ranger with a 4.0 SOHC engine that is fresh rebuild it has about 7500 miles on it.
The engine runs good my problem that’s really bugging me are the trim levels, warmed up at idle both STFT are at 0% =/- 1% , the LTFT is at around 4-5% =/- 1% when I take off at a normal pace the LTFT raises to 9-10% on both banks and staying there all the time until I let of the gas with the STFT staying close to 0% sometimes climbing to 2% or so but quickly correcting to 0% or close. If I really do a hard acceleration the LTFT goes up to 14-15% range until I let off with the STFT staying still close to 0-2%.
No DTC’s at all
MAF numbers are good.
O2 sensors are working correctly
Fuel pressure is @ 55-60 psi
EGR is at 0% at idle coming on to 35% at normal driving speeds
I’m starting to think maybe the wrong injectors were sold to me?

 

have you checked the ford product number on the old factory injector to the number on the new injector

chances are they may be a higher ( pound ) injector

 

Reads like your scanner has reversed the PIDs(packet IDs) for STFT and LTFT

STFT(short term fuel trim) should go up when you accelerate, computer is adding more fuel for more power
And STFT should be in + range at idle, richer mix prevents overheating at idle.

LTFT is slow to change, might change by 1 or 2 in real time, it is what it says, Long Term fuel trim, rear O2 sensor is also used for this.

So it reads like your STFT is really the LTFT and visa versa, and it all looks normal if that is the case

LTFT is used when engine is cold and O2 sensor feed back is not possible, so computer has a baseline of current engine air/fuel ratio trims that are working, i.e. small vacuum leaks, MAF sensor changes, fuel pressure changes, all effect air/fuel ratios as engine system ages, LTFT is used to offset those changes so on startup older engine runs OK until O2 sensors are online, a few minutes, or if MAF sensor or O2 sensor failure is detected LTFT can be used to keep engine working OK.
LTFT near 0 reads like a newer engine, or a rebuilt engine

STFT at 15-20 for a few seconds is normal, won't set a code, if it stays that high long enough it will set a code but only in memory, CEL won't come on, if high STFT levels repeat a few times then CEL will come on.


OBD2 PIDs here: https://en.wikipedia.org/wiki/OBD-II_PIDs

Scanner works by "requesting" data from Computer, Like "send me PID 06"(STFT Bank 1), it gets back 1 byte of data and changes that to a +/-% to display at STFT B1
PID 07 is LTFT Bank 1
PID 08 STFT Bank 2
PID 09 LTFT Bank 2

So if scanner is labeling them incorrectly or computer is sending then incorrectly then you would get what you have

You could check if your scanner has a software update or it could be your year Ford computer had a glitch and reversed PIDs for STFT and LTFT

 

I'll check with different scanner see what happens.

Ed