rough and low idle at stop

when i am at a stop or in park, my car idles pretty rough, and about 100rpm below normal. i have changed the plugs an wires, cleaned the IAC valce, cleaned the Throttle body, Cleaned the Throttle positioning sensor, changed most of the vaccume hoses and inspected others,ive done a torque test for the motor mounts, ive tested the fuel pressure regulator, and changed the fuel filter, brand new battery, ive done practically everything i can think of and the problem still hasnt gone away, i have 85k miles and no service lights or weird sounds...car runs smoothly when driving, smooth shifting etc.....im a little lost on how to find this problem, any help or advice is greatly appreciated, thank you.

I'm having a similar problem with my 2000 T&C with a 3.3. It will surge up and down in rpm at idle. It stalls at stops. Very annoying. Any ideas?

so far ive gotten a couple answeres, for you id suggest testing all the things that i listed that i repaired, its all in my first post, for me im gonna run a pressure test on the fuel rail, possibly replace the IAC valve, and double check for a clogged cat....also im hearing alot about a vaccume leak by the mapping sensor....but for you id check for a serious vaccume leak, or a fuel related problem...try checking your fuel pressure regulator, egr valve, iac valve and ur plugs and wires.