So its a 01 ranger edge 3.0 5 speed manual reg cab reg bed 2wd with about 228K on it.
Always starts right up, in the last 20 K miles or so ive done plugs, wires, coil pack, IAC valve, cleaned MAF twice, new air filter, ran numerous fuel injector cleaners thru it (but none lately).

I dont believe the brakes are dragging - they do have issues stopping but that should be un related. I can drive at highway speeds for 20 min, coast to the side of the road, hop out and feel the hubs/lugs and its not even warm so i dont believe i have dragging brakes.

The problem is i usually get about 20-22mpg depending on how much highway driving i do, we are still on winter blend gas so usually 20-21mpg or roughly 300 miles to a tank before i need to fill up. Lately as in the last 2 weeks or so i feel like its down on power, seems to run smooth but does seem to want to die occasionally as i try to take off from a stop, idle does sometimes kinda dip low for a second, does seem to take more gas pedal in 5th to stay at higher speeds. Last fill up driving the same routes as always i got 17 mpg, this tanks looking even worse as ive only gone 200 miles and below 1/4 tank from full...
No check engine lights.

I did read where the MAF can be dirty - affect performance and fuel economy but not set a check engine light. Got the special cleaner out and cleaned the **** outa it without touching the wires. Seemed like power was a bit better but may just be placebo. So today after getting off work and driving home, engine nice and normal temp i heard the truck should keep running when unplugging the MAF - i unplugged it it waited a second or two then truck shut off. What does this tell me? Google seems conflicting where some say it should run but will ignore the sensor using default values others say it should die.

oh and tire psi is normal.

 

I would suspect, according to your mileage, that your O2 sensors may not be as efficient. They do wear out. They usually won't cause a CEL unless they completely fail. If you have a OBDII reader that shows live data, it could give you a better idea of what's going on.
You may also want to clean your throttle body and your IAC valve and passages, even though you've changed them. Signs of excessive soot can be a clue. Check PCV and other routine maintenance items, ie. spark plugs, wires etc.. yes, even "new" ones can prematurely fail. Also, you don't mention fuel filter or if you've checked fuel pressure.

 

I have changed both up stream o2 sensors late last year, rear one i have not due to it being stubborn as hell to get out but that one just monitors the cat function and shouldnt have any effect on engine running.
PCV has been changed in the last year (oil level doesnt change either and smells/looks normal)
fuel filter was changed a year ago.
I do have a scan tool that shows live data but not sure what i should be looking for

 

You do want to get the rear O2 out and change it
While its not directly related to air/fuel mix it CAN cause rich running
Cats work by getting HOT yet they are not using 12volt power???
They use unburned gasoline to heat up, and use that heat they burn off toxic gases

O2 voltage is
0.1 Lean, high oxygen in exhaust
0.9 Rich, low oxygen in exhaust

So the computer constantly cycles a rich fuel mix to keep the Cats HOT
It does that based on Rear O2 sensors voltage, should be 0.7-0.8 volts low oxygen, the oxygen is used up to burn toxic gases, this means Cats are hot enough
If rear O2 is showing lower voltage then computer sends more gasoline thru to get Cats hotter

But your drop seem more that just that, but its IS a part of it

Exhaust manifold leaks cause a False Lean, air will be sucked in to manifold and upstream O2 sees that as Lean, high oxygen, so computer adds more gasoline to the mix and engine is running Richer than needed
You can look at spark plug tips, they will show if engine is running rich, darker brown color

Partially clogged exhaust, this also causes False Lean AND reduced power, so BOTH symptoms you describe
You can test for that with Vacuum gauge
engine vacuum should be 18-21" at idle
blip the throttle, open it all the way and let it snap closed, should see vacuum drop to 0 and then quickly come back above 21" and then back to "normal"

Raise RPMs to 2,500approx.and hold there, then watch vacuum level, if its slowly dropping exhaust is clogged, back pressure is building up

 

Ok i hooked my scanner up on a fully warmed up engine (scanner says coolant temp 190*F) and heres what i got for live data:
calculated LOAD value: 35.3%

Short Term Fuel Trim - Bank 1 - fluctuates rapidly between -1.6% and +1.6% and everything in between
Long Term Fuel Trim - Bank 1: steady at 2.3%

Short Term Fuel Trim Bank 2: between -1.6% and +2.3% and everything in between fluctiating rapidly
Long Term Fuel Trim Bank 2: steady 0.8%

Engine RPM ~850 rpm fluctuating around that
Ign timing for cyl 1: fluctuating between 17.5 and 19 degrees
Intake air temp: 60*F which was probably right for today.(within 3*F)

Air flow rate from Mass Airflow Sensor: 0.5-0.6 lb/min
Absolute throttle position: 16.1%

O2 sensor output voltage B1-S1: 0.085 to 0.705V fluctuating rapid between high and low
Short term Fuel trim B1-S1: -1.6% - +1.8% fluctuating between
o2 sensor output voltage B1-S2: 0.765 - 0.770V and rather steady
Short Term Fuel Trim B1-S2: 99.2% and steady
O2 sensor output voltage B2-S1: 0.075 - 0.730V fluctuating rapid between high and low
Short Term Fuel Trim B2-S1: -1.6% - +1.6%

Thats all i got for live data and from what i can google search that all seems ok i think...

I will try the vacuum gauge. Do you have a good port to tie the gauge into?

it could be plugged/partially plugged cats. Has friggin 5 of them on there.(Low Emissions Vehicle)

 

All those numbers show MPG should be fine as far as computer is concerned

Any vacuum port on the upper intake, if there are no unused/capped ports then just pull off a smaller hose and put vacuum gauge there for testing


If you are using odometer for part of MPG calculation then that could also be the problem, worm gear on odometer was failure prone, so odo can stop and start randomly, so would show lower miles than actually traveled
But wouldn't cause lower power

 

Yea i was wondering that about the odo... i reset the tripometer as well - they use the same drive gear or no?
i write down every fuel fill up in a little book, date, odo reading, and gallons put in. usually get about 300 miles to a tank, just filled up today and got 220 miles to like 12.5 gallons = ~17.8 mpg.

like i said i cleaned the MAF and it seems the power is a bit better. Will try on this tank and see what it gets while i hook up the gauge and report back what its doing.

question on the MAF reading : i know its supposed to climb up as engine rpm goes up - do you have the other RPM specs? like at 2500 rpm what it should read?

Thanks for your help!

 

Most measure MAF data at grams per second, gm/sc, so change reader to show that

General rule of thumb is liter displacement(3.0l) grams at idle of 500rpms, so at 800rpms you would see 4-5 gm/sc
You would need to look around for other 3.0l readings at different RPMs

 

Got it. Reader is a bit wonky being chinese made translated to english but the unit converters out there say .6 lb/min is about 4.5 gm/sec so its right where you say it should be.

Ill get readings at various RPM's tomorrow and post back and try to find some more info out there. I did rev it and it does go up as it should - just not sure if its going up enough at X rpm...

thanks for your hlep!