Chrysler Repair: 99 Durango: wont idle, cast iron pipe, exhaust gas recirculation valve

Question
when i start the truck, it fires, starts to run, then the rpms go to zero, and it dies. i can start it with my foot on the gas, manipulate the rpms, run it at a steady 1,000 1,500, or 2,000 rpms, but when i take my foot off of the gas it goes to zero rpms and dies. the check engine light never goes on and it comes up with no codes. all the fuses are good and it was running fine before this started. what's up with my truck? thank you.
.b

Answer
Hi Barry,
I don't claim expertise on the truck engines but what you are describing (no idle with no codes) sounds to me as if the exhaust gas recirculation valve is stuck slightly ajar instead of being closed tightly. When that happens the recirculating exhaust gas that is introduced into the intake manifold leans out the mixture too much to sustain an idle. I don't have a manual that covers your engine so I can only tell you that you would look for a small cast iron pipe that branches off of the main outlet of the exhaust manifold (one of the two manifolds if you have a V engine) and runs to the area of the throttle body. Near that point you will find a metal valve that controls the flow through the pipe back into the manifold near to the throttle body. It will have a round top connected to a vacuum hose and the main body of the valve will be mounted in that pipe. Between the round top and body there is an open flange inside of which you will see a rod with a slot in its circumference. That is valve stem which opens and closes the valve when it moves toward the round top and closes the valve when it moves back into the valve body. The closing action is supported by a spring in the valve body. You can take the tip of a screwdriver and insert it in the slot and then move the stem back and forth and test whether it moves smoothly and closes tightly to a stop by means of the internal spring. If it seems sticky in that action then take some WD-40 and spray the stem at the point where it enters the body of the valve so as to free up the valve action and verify that the stem comes to a firm stop on its own power.
Then try and start the engine and see if it will idle.
Please let me know how you make out with this fix.
Roland