I have searched around the forum and have found some useful threads. But this is still stumping me.

2000 5.9l Durango 4wd Automatic 173k miles

It started out randomly and would idle spratically and really low below 500 and bouncing from 500 to 1000, most of the time it was usually off a cold start when it warmed up it would quit.

Now it does this all the time with the AC on or off, it idles up and down and drops below 500rpm and shuts off most of the time if it doesnt cut off its a really low idle.

I cleaned the throttle body, took the IAC out cleaned it and cleaned the hole out it goes in. The crank case vent line was disconnected I hooked it back up. I must have knocked it loose checking fuel lines. My fuel pressure is a solid 50 at key switch on. If I crank the truck and hold my foot on the pedal its about 48-50, if I let off and let it do the rough idle the fuel pressure gauge flickers back and forth between 45 and 50.

The only way to crank the truck is give it a little gas while starting and it fires right up. While driving I have no skips or problems out of it only when I let all the way off the gas.

Any help and assistance is greatly appreciated.

 

Sounds to me that it could be a few issues that come to mind... I'll just list my thoughts and you can go from there..

1.Bad TPS (throttle position sensor) - Get yourself a multi-meter and with the truck on (NOT RUNNING) but at the key put the red probe in the middle led wire and the other grounded somewhere... manually move the throttle to wide open, you should be getting 4.5-5 volt and as you slowly close it the volts should drop... if you get anything less replace the TPS.

2. Bad IAC

3. Weak battery - If you have a battery more the 3.5 year old i would just replace it. these trucks can reach havic if the volts are not right.. Don't trust a chain stores battery test either.. i have had many test ok and where bad.

4. Failing plenium gasket - While unlikely it is causing your issue i have seen some report similar issues and that being the cause. Take off you air hat open the butterflies and look down in there with a flashlight... if there are major puddles of oil in there it's blown... again do this with the MOTOR OFF!

5. In need of a tune up - plugs, wires, cap, rotor...


just my thoughts im sure others will chime in later on...

 

I have also been having similar issues with a 2002 4.7. Replaced all sensors, have checked fuel pressure, changed battery. Problem with mine is you can hear a vacuum leak coming from somewhere -near- the front center of the motor. All lines have been checked. Also replaced intake gaskets. About 2 weeks after I bought it about a year ago the check engine light came on and ended up replacing the purge solenoid and gas cap and reset the light. It still came on with the same code but never had any problems with it until now and I'm starting to run out of affordable options.

 

Take carb cleaner and spray down any vacuum lines/intake manifold sealing surfaces. If you have a jump in rpm's you found your vacuum leak.

 

Did that too. Never had a jump in rpm's but when we sprayed around the front of the motor the rpm's would actually drop and it would die.

 

Maybe it is choking on the stuff. Start at the front of the engine and just give it a little squirt here and there to try and pinpoint it.

 

Did that again and got the same thing. I'm starting to think it's a lost cause.