So I have a 97 2.3l ranger that i bought as a project at 18 years old Im 19 now and ive learned lots from the truck. But, Ive got a high idle and I've replaced lots of parts to no avail. Iacv, vaccum lines, PCV, throttle ps, and cleaned out my air intake and throttle body. It did have a throttle body spacer but I removed it because after some digging around it turns out there is no power gain or better mpg. (The previous owner had it installed). spark plugs still have lots of life in them and i recently put in new spark plug wires also because I dont really trust the 25 yo wires. I dont know what to do! Is there a relearning cycle that im supposed to do? Or am i missing something? Please any info will be greatly appreciated!

(how the truck acts)
on a cold start the rmps jolt immediately to 2k rpm and then bogs down to 1.5k rmp as the engine warms up. the lowest it goes is 1200 rpm. When coming to a stop the rps go up to 2000 rpm then goes down to 1500 at a full stop. And when pressing the clutch when rolling the rpms go up and down.

i have a p1506 code

 

Welcome to the forum

Good Ranger
2.3l Lima engine, 1997 was last year for the 2.3l, was stroked to 2.5l in 1998
First used in a 1974 Pinto, so good reliable engine or Ford wouldn't have stuck with it so long

P1506 Idle Air Control Overspeed Error

So computer is recognizing the high idle and is mostly not causing it

If you look on the throttle body there will be a screw stop for the throttle plate(on throttle cable linkage), this is an "anti-diesel screw" but looks like an idle screw, lol
Some one may have mis-adjusted it

To reset it
Warm the engine up, and let it idle
Unplug the 2 wire connector on IAC Valve
RPMs should drop to about 600rpms or engine may even stall, either is good it means no vacuum leaks and anti-diesel screw is OK, you could turn it up a bit so engine doesn't stall
But this may also mean the Computer was causing the high idle, so computer error, it was holding open IAC Valve too far

If RPMs do NOT drop with IAC Valve unplugged, then adjust the anti-diesel screw counter clockwise to lower the RPMs(close the throttle plate more) until engine is barely running, about 500-600 RPMs, don't need a tachometer, just barely running is good
Screw is set
Plug back in the IAC Valve and RPMs should go up to 750 with manual trans or 800 for automatic, these are warm engine "target idles" in computers memory
Engine should idle higher when cold, its based on engine temp, colder it is the higher the idle

P1506 code should go away and you might get "IAC Valve unplugged" code, but it will go away as well


And just a heads up on your 2.3l
It has dual spark plugs for extra power, both spark plugs fire at the same time, no alternating, or there would be no point to dual spark plugs, lol
What you should do every year or when you feel like it, is to unplug the 3 wire connector on one coil pack, move it back so it can arc to coil pack
Start engine
If should idle smoothly, if not then you have one bad spark plug on that working coil pack
Shut off engine and do the same test on other coil pack

The 2.3l engine ran fine on 4 spark plugs from 1974 thru 1988 so will still run fine on 4 spark plugs in 1997
But you can't tell if one spark plug fails in the dual plug setup, you just lose a bit of power
So best to test that all 4 spark plugs are working on each coil pack
And you can drive it, if you want, on just the 4 spark plugs to see the power difference, doesn't hurt anything, it will set a trouble code(CEL, check engine light, comes on) with coil pack unplugged but it will go away once its plugged back in

 

So I did the steps that you told me about the screw and the iacv and it worked! Now im idling at around 850 900 rpm, I also lubed up the retrun spring on the throttle body. Now she doesn't bog down when i put in the AC nor does she hold idle when i rev it up in neutral. Thank you for the help Ron!

 

Good work

Thanks for the update and THE FIX, it will help someone else down the road