Rough idle and high bank 2 fuel trims

Vehicle: Listed above SOHC non-Flex.

Symptoms:
-Hard start (sometimes need to depress gas pedal)
-Rough idle
-Very rough idle when put in gear

Error codes (from a old cheap handheld scanner)
-P0174, which I understand to be “too lean (bank 2)”, and bank 2 = drivers side, where cylinders 4/5/6 are.

First thing I did: some general maintenance, some of which I have been delinquent on and some of which didn’t think would cause my issue, but was already in there so replaced to rule out. Did the following:
-Cleaned throttle body
-Replaced spark plugs
-Replaced spark plug wires
-Replaced ignition coil
-Replaced fuel filter
-Replaced PCV valve
-Replaced mass airflow sensor
-Replaced fuel rail pressure sensor
-Replaced air filter
-Replaced intake manifold gaskets
-Replaced left (driver) upper O2 sensor
-Replaced right (passenger) upper O2 sensor

**No change in behavior.

Second thing: built a smoker and checked for vacuum leaks. EGR valve (original) was leaking some.
-replaced replaced EGR valve

**No change in behavior.

Third thing: Evap purge hose going to top of intake is pretty sketchy looking. Removed from intake and plugged intake port, in case either hose or the purge solenoid is bad.

**No change in behavior.

Fourth thing: bought a Bluetooth OBDII scanner (amazon, BAFX scanner) and loaded FORScan on a laptop – maybe it doesn’t take much, but I’m really impressed with what one can do with $23 and free software!
-scans show long term and short term fuel trim on Bank 1 to be +/- 5% - and stay that way as a crank RPMs up
-scans show long term and short term fuel trim on Bank 2 to be very high, LTFT2 pegged at 25%, STFT2 near 20%, and increases with higher RPMs
-data looks something like the attached image

Fifth thing: with the STFT2 and LTFT2 staying high as a increased RPMs, I concluded that this didn’t look like a vacuum leak, or at least if it was it was a really really bad one, which my smoke test didn’t show. So I thought maybe we’re looking at clogged or dead injectors. Put a mechanic’s stethoscope on the injectors I could get to (easy on bank 1, bank 2 harder) and all seemed to be clicking away. So I cleaned them and swapped them
-Removed injectors, noting cylinder position
-Cleaned with carb/throttle body cleaner (attaching a tube to the injector, putting cleaner in tube, putting 20 lbs of compressed air on tube, actuating injector by manually pulses the leads with a 12v battery
-all injectors fired
-Reinstalled injectors, but put bank1 injectors in bank 2 and vice versa
-New o-ring seals
-Before completely installing, test cranked engine with the fuel injectors hanging off the fuel rail. All injectors fired.
-Put everything back together

**No change in behavior.

**note, while doing this, went ahead and pulled the valve covers to check out the timing chain. Bank 2 chain is tight, no visible signs of cassette failure. Bank 1 chain had a little slack, no visible signs of cassette failure. New gaskets used when re-installing the covers.

Sixth thing: scan again. STFT2 and LTFT2 still high. Bank2 is high with what was bank 1’s injectors. So I think I can say the injectors are okay?


So now I’m scratching my head a bit – what to check next.

1-Exhaust leak before O2 sensor? Take my smoker and put in my exhaust and see what happens

2-Injectors? Double verify that injectors, fully installed, are injecting? Pull plug wires, crank, and see if plugs are wet?

3-Fuel pressure? This explorer don’t have a test port on the fuel rail. Could there be a clog in the pressure rail at/before the bank 2 side? Would weak fuel pump cause this kind of behavior? How best to test fuel pump pressure? Don’t really want to just replace fuel pump.

4-Vacuum leak – double verify no vacuum leak? Have the laptop plotting LTFT2 and STFT2 and spray propane around intake, brake booster, vacuum lines?

5-Timing – double verify bank 2 cassette didn’t explode and timing is whack? Best way to do this? Pull off oil pan and look for chunks of plastic?

6-?

So thoughts? Comments? Suggestions?