Rough Idle/Check Engine Light Flashing

04 Ranger 3.0--Idles rough after warmed up then check engine light comes on and begans to flash..Replaced plugs,plug wires,coil pack,fuel relay switch and fuel filter so far..I get a random misfire code and occasionally a misfire on #4 or #6..Fuel consumption is ridiculous (burned a quarter tank of gas on a 55 mile round trip)..I'm wondering if I might have a bad O2 sensor although no codes indicate that..Also, short term fuel trim at -6/ long term at 7 at idle..Any help would be great.

You need to get more data from live scanner.

You will have bank 1 and bank 2
Bank 1 is cylinders #1, 2 and 3, O2-1
Bank 2 is cylinders #4, 5, and 6, O2-1

STFT(short term fuel trim) is just that, live(appox. 5second delay) fuel changes caused by O2 sensor #1 data on that Bank.
It should be jumping around, that is normal, if numbers are changing slowly then replace O2 sensor on that Bank, it is wearing out and can't see the changes fast enough.
+ % means lean and fuel is being added
- % means rich and fuel is being reduced

0 is the target 14:1 air/fuel mix

LTFT(long term fuel trim) is an average, over time, on whether fuel is being added +%, or fuel in being reduced -%.
0 is again the target but +/-10% for LTFT is consider within normal parameters.

Cold starts are a rich mix, engine is running in Choke mode until it warms up.
Idling is set to be a rich mix so stop and go traffic will bias LTFT.
As will long drives at highway speeds.

Idle is a poor test of STFT, run engine at 1,500rpm for a mile or two, and then at 2,500rpm for a mile or two and see what numbers you get, also see how LTFT changed from before the drive

FYI
O2 sensor #2 is the one(or two) that is(are) located after the Catalytic converter, this is used to tell if Cat converter is working to clean exhaust.

O2 sensors can wear out just like spark plugs, the spec is 70-100k miles, outside of a total failure the computer has no way to know if O2 sensor is giving it correct Oxygen content of exhaust, so no code would be set.
But it can detect if sensor is not reacting fast enough or correctly in some cases, computer is always changing fuel/air mix slightly, which is why STFT numbers jump around, if O2 sensor doesn't "see" a rich or lean change the computer just made then a code would be set, usually in history but could set CEL if it was an on going issue on that Bank.

The "downstream" O2 sensor(s), after the Cat, rarely wear out, they see a cleaner exhaust after the Cat, they can only effect air/fuel mix slightly, and usually only if there is a problem with "upstream" O2 sensor(s).

You could have a dirty MAF sensor, easy to clean.

You could have dirty injector tips, these drip fuel instead of spraying fuel, causes a drop in MPG and misfires, Seafoam or similar gas treatment once a year helps prevent this and cleans tips that are already dirty.

You could have a sticky injector, not closing all the time causing rich mix on one bank and drop in MPG.

There is a method to "clear a flooded engine" in all EFI systems.
Turn key to RUN(on)
Press gas pedal down to floor and hold it there.
Turn key to START, Crank engine.
Engine should not fire at all, spark will be on but fuel injectors will be shut off, a leaking injector would cause engine to fire intermittently.


Also what did the old spark plug tips look like when removed?
Especially Bank 2, cyls 4, 5 and 6

EDIT:
There is also the common issue with PCV hoses on the Rangers, they get cracks and holes, almost a 100% failure rate when they get 10 years old(thanks adsm8), worth a look for sure, under side of elbows is the common failure point.