Here is my head scratch-er:
-I have an 05 FX4 with 4.0L engine, (it's actually my daughters I just work on it pay bills etc...) She called me last week complaining that the truck stalled on her way to work, the truck started right back up so told her to drive home at end of day. When she returned home she said that it stalled 3x's... So took it out for a test drive as I don't always understand 19yr old girl vehicle problem descriptions. That said yes the truck stalled out when in drive. I have gone thru just about everything I can think of to check and am looking to find out if anyone has run into this problem?
Items Checked: ( I would like to note that there are no codes at the beginning of the search and thru out all the checks and replacements following).
Fuel Press (65psi constant even when stalling out), MAF (Cleaned and tested), IAC (replaced) Crank sensor (Replaced), Cam sensor (checked), Knock Sensor (replaced, mouse had chewed threw wire).

After putting the intake manifold back on I took it for a test drive and have noted that if I keep the RPM @ or below 1100 the truck will not stall, If the truck is in reverse you can mash the gas and it operates flawlessly otherwise with normal acceleration the engine will die within 10-20 ft. I would like to add that each time it stalls it will start right back up no problem (the symptoms seem to be getting worse). also when it is stationary (under load or Idle) it does not stall or hic-up.

Have had it at a Mechanic and we drove around for approx. 20min with his code reader on it and at the end he said "yes, there is a problem"
Any Help would be greatly appreciated.

 

I hope this might help.

I had a similar problem a while back (in a 01 with a 4x2) with all the same symptoms. I checked everything and noticed that there was water in the airbox, Ford did not include drain holes in the boxes for the Ranger and the engine sucks it right up and stalls, only in high RPM where air intake is high. this does not trip any trouble codes. I would check the box.

Also have a look at the electrical setup for the 4x4 settings it may be trying to switch in 4H/L while in drive. Im not 100% sure though don't own the 4x4.

 

Unplug the IAC valve and start the engine, you should get a CEL and IAC Valve code instantly, just a sanity check on computer, you want to see if the IAC section is awake and working, lol
Computer uses the IAC Valve to prevent engine from stalling, and its a very accurate system(+/-3 RPM) and very fast to respond

When you start a cold engine RPMs should go up to 1,100 or so and stay there, thats the ECT sensor, IAC Valve and computer all working and in CHOKE mode, high idle, advanced spark, rich fuel mix, choke mode
As engine warms up RPMs should go down, and settle in at about 750-800rpms warmed up, 800-850 when in gear or when AC compressor is on, its on in Defrost as well as AC on


The DTR sensor on the automatic trans tells computer when trans is "in gear", and you should feel the idle RPMs "bump up" when shifting from Park or Neural into any gear

The TCC solenoid locks and unlocks the torque converter, has the OD light on the dash ever flashed?
This means a transmission code has been set, most OBD2 readers can't see these codes, P07XX codes
If the TCC solenoid is sticking then engine would stall when you tried to stop, but you should "feel it" pulling, not coasting, would be the same as trying to stop a manual transmission in gear without pushing in the clutch engine stalls


And in the end it may be a computer issue
2005 does not have PATS, Ford Rangers skipped that year
But computer is "married" to the instrument cluster, so you can't just swap in a new computer, only Ford can
You can swap in a set, a 2005 cluster and it computer, from another 4.0l Ranger, doesn't need to be FX4 or even a 4x4, that doesn't matter

 

Thank you for the response -There was no noticeable water in the air box, As to the 4x4 settings how would I check that do you know?

 

Thank you I will check your suggestions and revert.

 

Thanks RonD & Browmic,
The Ranger is working again. I ran thru both your suggestions, then Jacked up the truck and started to fiddle with the wiring for the transfer case and found that the bundle for shift module was rubbing on the drive shaft and had worn thru the wire loom and into 2 wires. It was funny that you mentioned that Bromac, as I had just had the tranny swapped out 3 mnths ago by a Mech shop that came with a great rep. However when the I got it back I checked the work and noticed that he had not reinstalled the vent line on the transfer case. I should have gone thru all his work as he had not routed the harness properly, "Sloppy". Point being twist your own wrench as much as possible because nobody loves your truck and your safety as much as you do. Thanks to this forum and your help.