Old ranger issues
 

I have a 2004 ranger with the 3 liter motor and auto trans.
It has a horrible idle with p0301 and p0300 codes as well as p0172 and 175 (runs rich) codes.
This truck has 400,000 kms on it which I guess is around 300 miles.

Anyway it has new plugs, wires, coil, fuel filter, air filter. Ive carb cleaned the MAF sensor and cleaned the Idle control valve.
The fuel filter has helped the idle the MOST but its still a rough idle.

Suggestions on what to do next? The fuel pump is audible on start up but I can't confirm how strong it is.

Welcome to the forum

Shouldn't use carb cleaner on MAF sensor, or any sensor for that matter
You need a low residue cleaner, electronics cleaner
For controls it is fine to use, like on IAC Valves

I would get another MAF from wrecking yard, should run maybe $30
Unplug current MAF sensor and see if engine starts, and if so, if it runs better, not great just better

What did the old spark plugs tell you?
color of the tips?

Test for leaking fuel injector
Engine warmed up and off
Turn on the key
Press gas pedal down to the floor and HOLD IT DOWN all the way
Turn key to START
engine should just crank
It should NOT start, it should not fire at all

Fuel injectors are off, spark is on, this is called Clear Flooded Engine routine
Key on, engine off(0 RPMs), Throttle Wide Open = Clear Flooded Engine

If your engine fires or starts then you have fuel leaking in

ok I will look more in to the maf and do the pedal trick later today.
As far as the plugs they were old and worn down although i'd say some of the plugs had more carbon than others while some of the ceramic portions had more white still showing

OK MAF sensor did nothing however it fired right up with the pedal to the floor so its fuel injector related right? Where do I go from here.

First check that gas pedal to the floor OPENS throttle all the way
Put something heavy on gas pedal then go to engine and see if you can open throttle a bit more manually
If you can then you never got into Clear Flooded Engine, so any engine would start

Google: Ranger throttle cable mod

Very simple fix for stretched throttle cables, couple of zip ties and your done, then retest

If you KNOW you were in Clear Flooded Engine routine and engine still started
THEN
Disconnect Coil Pack's 4 wire connector, so no spark
Do Clear Flooded Engine test again but crank it a few times, pedal to the FLOOR
Now pull out the spark plugs, one at a time
ALL will be DRY except to the one with the leaking injector