I have a 2006 sport 2wd. I was driving the other day and my Rpms dropped from normal driving levels to about 750-1000 and my motor started to make a very loud squeal, so i pulled over and shut off the truck and started it up again and the squeal was louder and the rpms were even lower and it i tried to hit the gas the truck would rev to 1500 and stay there but when i let off the gas the truck would sputter and almost die then go back to about 700 rpm. any ideas on what could be the issue??

 

Welcome to the forum

The squealing is the fan belt, so may need a new one and maybe a new tensioner for the belt

The low RPM caused the squealing, so you need to find the cause of the low RPM

You need a Volt/OHM Meter, $10 volt/ohm meter will save you hundreds of dollars over the years

First, just to take it off the table, test battery voltage, key off, 12.3 to 12.8 volts is acceptable range for a car/truck battery, 12.2v or lower means there is a battery or alternator problem
Test it, even if you got a new battery this morning, lol

Fuel injected engines all use an air valve to control idle RPMs
Ford calls theirs an IAC(idle air control) Valve

Your 2006 2.3l Ranger IAC Valve looks like this: https://www.ebay.com/itm/1113873-Idl...-/222610916191

It is located on the on the upper intake manifold next to the throttle plate/cable

It has 2 wires connected, unplug the 2 wires and use volt meter, set to 20vDC, to test if they show over 11volts with key on, engine off

Then test IAC Valve's pins with OHM meter set to lowest scale, 200OHMs, should show 9 to 10 ohms, then test either connector to metal case of the IAC Valve should be NC, no connection, or ohm meter value doesn't change, stays at 1

If everything tests OK then IAC Valve is not the problem

Could be vacuum leak or an EGR issue

 

Are all the pulleys turning when the engine is running? Had an A/C compressor lock up and truck did the same thing.

 

Good call Grumpa, never even though of a seized pulley