I’ve changed fuel filter and fuel pump I have p0174 and p0171 Codes, I have great reason to believe it’s a vacuum leak but I’ve checked the hoses a million times and nothing then I noticed a stub missing on the exhaust intake so could the leaking air from the exhaust manifold trigger the lean codes or can that be from a vacuum check it’s lost a lot of power it stalls when coming to a hard stop i know I need to change my ignition switch but I’m still having lots of issues I had to take my girl to airport early this morning but it was putting the whole way there idk what to do I’ve worked on this truck for so long and my truck idles at 500 it’s a 98 ford ranger xlt 3.0l 2wd I really need some help hear

 

Welcome! Have you checked on the 90 degree hose at the end of the intake manifold? When mine went bad and started to crack, it would collapse and it allowed un-metered air into the engine and the truck would die when I would come to a stop. Here is a photo of mine after replacement with the "newly" improved design with ribs to give it more rigidity.

 

+1 ^^^

P0171 Lean on bank 1(passenger side)
P0174 Lean on bank 2(drivers side)

This means the computer is having to open the fuel injectors longer than it had calculated for the amount, and WEIGHT, of the air it used in its calculations
It doesn't mean the engine is actually running Lean

O2 sensors see Oxygen, not fuel, computer uses upstream O2 sensor to see oxygen in exhaust manifold on each bank
So an exhaust leak one one manifold can cause a "false" Lean but just on that Bank of the engine, not both banks
Too much oxygen in the exhaust manifold = Lean burn, too little oxygen is a Rich burn

Since you have BOTH Banks showing Lean codes it won't be from an exhaust leak on one bank
It needs to be a common issue that BOTH Banks use

Fuel pressure was a good place to go once you took major vacuum leak off the table
1998 and up Ranger need 55-65psi fuel pressure, so what is your pressure now with the new pump?

Idling at 500rpms after warm up seems low for 1998 3.0l, assuming manual trans, as automatic WOULD stall at 500rpms in gear
It also means no major vacuum leak
Air = RPMs, thats how the throttle plate works on all gasoline engines, it lets in more AIR and that increases RPMs, if you just add more fuel you get a flooded engine
So vacuum leak always = higher RPMs

And 171/174 are the only codes?

Try unplugging the MAF sensor and see if it drives better

 

I replaced the heater valve cause it was falling apart in my hand and still no fix I’m half tempted to do a rebuild on it what do you think ,also I had replaced the maf sensor awhile ago and still no fix I unplug the iac valve and the cars acts ilas if nothing happening it stays at the same idle of 500 rpm I half gas or oil or some sort leaking onto my exhaust manifold and starting to leak from the bottom of the engine

 

I’m gonna give you all the codes it’s reading meB1428. P0102 P0230
B1323. P1504. P0231
b1359 P1507
c1095. P0171

 

no P0174??

B and C codes are for body and chassis so not engine related

P code is powertrain so engine or transmission related

P0102 Mass or Volume Air Flow Circuit Low Input<<<<can cause poor running, try cleaning it

P0230 Fuel Pump Primary Circuit Malfunction
P0231 Fuel Pump Secondary Circuit Low
Could be from you testing fuel pump system, if you didn't then replace Fuel Pump relay in the engine fuse box
These codes mean fuel pump was not getting 12volts when it should have

P1504 Idle Air Control Circuit
P1507 Idle Air Control Underspeed Error
These codes are for IAC Valve, was it unplugged from power for testing?
If not it may need to be cleaned

 

With all those Circuit Failure/malfunction, My first guess is you have bad or missing grounds. or a bad PCM/ECM

 

When I unplug the iac valve car acts as if nothing happened and stays at a rough idle of 500 I cleaned the iac valve once awhile back but idk if maybe it didn’t get the proper cleaning as needed I believe I used a carb cleaner (mb rookie mistake) but even after car still would run rough I just got my hands on a voltage meter I’m gonna our out that is my first car and I’m doing this all myself so I may be slow at times but I’m doing my best so correct me if there’s any issues from my diagnosis

 

Can someone message me and help me out on a different line of communication I’m having troubles navigating through this site, also I’d like to conclude that when I’m at idles my dash lights dimmer and my heater turns down when I let go of gas