I’ve had my ‘99 Durango 5.9 4x4 for just over a week now. I’ve had nothing but issues since purchase. Specifically at red lights and warming up before leaving for the day the engine will stall unless i rev up the RPM’s. I’ve replaced IAC, MAP, TPS, Air filter, Spark Plugs, thoroughly and properly cleaned TB AND replaced TB gasket, and I’m lost where to look next. I brought into mechanic who said it was IAC or IAC short between IAC and PCM. He said he couldn’t do any further testing and referred me to an electrical expert. She starts up fine but after about 5-10 min the idle drops from 800 rpm to 500-300 then without revving up it will stall. Highway driving is a dream but in the city this is killing me and I just want it fixed no mater the f****** cost. If anyone can be of help let me know. This is a mudding BEAST and I hope to bring her out with our fleet this spring if she’s up to par. I should also add the previous owner was a heavy mudder aswell. Could the fuel pump or filter be causing this? Is the mechanic onto something with a short between IAC & PCM? Do I have a faulty PCM? If ANY other info is needed I will promptly give it. I will be watching replies to this thread constantly. I’m looking to have this bad boy fixed as soon as possible because even thought the MPG is **** I absolutely love driving my rango! Only codes it’s throwing are IAC & o2 sensors BUT it is straight piped and o2 sensor harnesses are ripped out and taped off.Thanks for all the help in advance! Ps I am taking it upon myself to make sure if the problem is resolved to post the end result. Specially because if other owners had done the same I wouldn’t be posting this thread in 2020.

 

I should also add the Cruise Control does not work, if it’s any help.

 

Try disconnecting the front O2 sensor, and see if the behavior changes.

Cruise control is a separate issue.

 

Is the front one before where the catalytic converter used to be or in engine bay?

 

No noticeable change when unplugging front o2. Codes it threw were p0138 02 Sensor shorted to voltage. P0172 fuel system rich. P0505 iac motor circuit short. I should note after I did relearn process for IAC codes p0172 & p0505 went away.

 

 

You either have a vacuum leak somewhere or the IAC just doesn’t work. I’d start by checking the IAC circuit, test to make sure it is actually getting voltage.

 

This, the P0505 points at your problem.

 

I will be doing some testing on PCM & IAC Harness/Wiring back into PCM. I have scanner on the way that will arrive tonight. I will record any live data you would recommend. I have a hunch it’s my IAC control circuit in my PCM. Will post updates

 

Not an uncommon failure.... Unplug the IAC, turn the ignition on, you should see 12 volts at two wires in the connector.