I have a 1999 Dodge Durango 4x4 with the 5.9L Magnum Engine. It has approximately 247,000 miles on it. It drives like a champion besides my current issue.
So, before I explain this, I would like to mention that this is starting the engine cold. When I start up the truck, it goes right up completely fine besides the RPMs going to about 1600 - 1700 RPMs. This is what it idles at and does not reduce the warmer the engine gets. When I put the Durango in "Drive", if I DO NOT touch the gas pedal at all, the vehicle will continue to climb in speed all the way up to 50 mph and will continue to drive this fast unless I press on the brakes.
Now, while the vehicle is in motion, it keeps getting a random but quick drop in RPMs as if it's going to start running properly but goes right back. Those random intervals are only about 1 second before it goes back to its high speed. If I press on the gas pedal and leave my foot on the gas pedal, these random short spurts do not happen. It only happens when it's in sense, "Ghost Driving."
With that being said, when the engine reaches normal operating temperature, the "check engine light" turns on. It's a solid check engine light. Never flashes. Shortly after this occurs, the vehicle now basically loses most of its power and starts giving quieter backfiring from the exhaust and begins stuttering at the same time. The truck will eventually die if I let it proceed to that point, if I don't turn it off. Once I turn the truck off, it will not start back up until the engine is 100% cooled down. Doesn't matter what I try.
Last thing I would like to mention is that when the truck is idling after startup and I don't drive it, it will continue to idle at 1600 - 1700 RPMs the whole time and in the midst of this, you can sit there and watch the exhaust manifold getting hotter and hotter to the point where it will start to glow red.
I refuse to drive the truck while it's like this. I would be destraught if something worse would happen to it. This is my only means for transportation and I need it up and running again.

 

Find out what the codes are and post them. Did you check for any intake leaks(pvc valve)? Has the plenum gasket been relapsed?

 

Problem is, I don't have an OBD2 scanner to be able to read the code being thrown out. I changed the valve cover gaskets towards the end of May. I replaced the map sensor back in February and I have actually tested this sensor since this problem had began because the symptoms that are happening resembled the symptoms of when the map sensor was bad. The map sensor is not malfunctioning or anything. Its working 100% completely fine.
Yesterday, I replaced all 8 spark plugs and bought a new PCV valve and grommet. By replacing these said things, the problem still persists but seems to be 'smoother' rather than 'rough'. The RPMs fluctuate slightly lower than before ranging between 1100 - 1400 RPMs. By fluctuate I mean that the needle on the RPM gauge goes up and down at the same speed. It goes up then down, up then down. It continues to do this repeatedly and does not change. Once the engine reaches its normal operating temperature and I turn the engine off, it refuses to fire back up. All it does is crank and occasionally give a slight single chug as if combustion were going to happen. It seems as if it grabs oxygen for just that split second but cannot continue to keep that source of oxygen.
I'm starting to think it could possibly be the TPS (Throttle Position Sensor) and/or the IAC (Idle Air Control Valve).


Plenum gasket hasn't been recently replaced.

Also, I would like to ask if there is a way to read the CEL (Check Engine Light) code by using the infamous paper clip trick? If so, which pins would I jump?

 

One way or another your problem is too much air going into the motor. You've likely either got a vacuum leak (could range from broken hose to plenum gasket), a bad IAC (idle air control) valve, or a stuck open throttle.

Most parts stores can read codes for you. There is a way to get them to show on the odometer. I forget the whole procedure, but search here for "key dance" and it'll probably some up. (Might be turn from off to run 3 times, the last time leaving it in run position (not started)).

Either way though, find the extra air and rm it's ***.

 

Take it to one of the parts stores that will read the codes for free. The plenum gasket is a major issue with these engines. Look down the throttle body(throttle full open) and see if there is oil at the bottom. Most likely there is with that many miles. Get the codes and go from there.
http://www.hughesengines.com/Index/p...p?partid=27091

 

I just took mine off.
I found oil I could not see from above, and a minor leak.
Explains my hot RPMs.

 

You don't need a scanner to check engine codes. Cycle the ignition key on and off 3 time leave it on the third time. Watch the cluster and your P codes will come up if you have any.

 

Also changed out the MAF and the TPS, but the O2 sensor was the main issue.