Chrysler Repair: 3.3 L: idles poorly, hesitates on acceleration, exhaust gas recirculation valve, side exhaust manifold

Question
The engine at idle seems like it wants to die, it shakes then goes back to a good idle.  Then I was on the freeway and wanted to accelerate to change lane.  It bogged, hesitated, then backfired from the engine area.  Someone told me it may be the catalytic converter. I just replaced it, van has 143,000 miles,however, it still stumbles when I want to stomp on the accelerator.  Is it some kind of fuel sensor, is the throttle body valve full of carbon? Or is it the fuel filter being clogged up/  

Answer
Hi Larry,
The only way to cut down on the numerous possibilities is to see if the engine controller has stored any fault codes in its memory. I don't know on a vehicle manufactured in 2003 whether you can get any codes using your ignition switch but try: "on-off-on-off-on and leave on" doing this in 5 seconds or less elapsed time. Then watch the odometer window to see if any P followed by 4-digit numbers appear. If not, get a readout at an Autozone for free, or pay a shop to do the readout (maybe around $40). Then ask what the codes mean and what might be the fixes. Write back and tell me the results if you wish some advice.
One part that might be causing this is the exhaust gas recirculation valve which is located at the rear of the engine near the air intake throttle valve. It is mounted in a pipe that runs between the right side exhaust manifold and the air intake manifold. The valve is mounted horizontally and has a valve stem between its round vacuum actuator top and the body of the valve which is attached to the pipe, inside the flange that connects the two parts of the valve. The stem has a slot into which you can insert the tip of a flat-bladed screwdriver so as to lever the stem back and forth against spring action (to close it) which should move freely and close tightly. If the stem seems to be sticky so that stem doesn't close all the way by spring action, then you can try spraying some penetrating solvent like WD-40 on the valve stem to freeup its motion.
If the valve is sticking slightly ajar it will make for a rough idle and poor acceleration at full throttle such as you describe because the mixture is too dilute. It is one of the most common causes of these symptoms. So see if you can find the valve and check/lubricate the stem. To check it in motion you can rev the engine from idle to 2500 rpm and back to idle and watch to see if the valve stem moves freely in both directions to the extreme open and closed positions. It may be that the interior of the valve is cruddy so that might require that it be unbolted from the pipe where it it attached and cleaned. But chances are good it will only be a sticky stem. Feel free to write back with the results and other questions you might have.
Roland