I have a 98 2.5 Venge with 210,000 miles. It started having problems a couple months ago with rough idling and hesitation. So far I have replaced the timing belt (maintenance, thought it couldn't hurt), water pump(while I had the belt off), o2 sensors(4 of them), IAC Valve, TPS (originally had a code for this, after replacement ran better at idle), Intake Air temp sensor, Fuel filter (also checked fuel pressure and it checked out), Crankshaft Position Sensor, Spark Plugs & Wires, Accesory belts & pulleys, tested the fuel injectors(also cleaned them with carb cleaner), Replaced gaskets in the throttle body and plenums, and ran seafoam through (which was a lot of fun). I also had to replace the battery. It now starts fine and idles ok in park, though a little under where it used to, but it idles very rough in drive, neutral, or reverse. The transmission fluid is fine, replaced properly a few months back. It'll drive for a while, but hesitates when accelerating, though it idles great when moving. It will stall randomly when coming to a stop, but will start back up almost right away. It'll then hesitate horribly until its moving. Any ideas would be very helpful. I'm thinking vacuum leak somewhere, but I can't locate anything. Would EGR Valve cause this?

 

YES Egr can cause poor idle ...

 

Would the egr cause poor idle all the time? it idles fine when in park.

 

when my egr crapped out it was idleing bad all the time ....

 

Ok, I fixed the problem. If anyone else has similiar symptoms, it turns out it was the distributor cap and rotor. Keep in mind that I just replaced these about 8 months ago, and didn't even bother to doublecheck them. The outside still looked in mint condition, but once I took apart the cap to check connections, it was apparent. Hopefully this is a reminder to check the obvious before we go replacing every sensor under the sun.