2002 Grand Cherokee Limited Idle problem

[dss56]

I have a 2002 GCL 4.7 engine. I have replaced the IAC and TPS because of the Idle problem I am having. I have cleaned the throttle body a few times and still have the idle problem.
I have had the problem for a few months and have posted this problem before but as time has gone by I have noticed that I feel it was never the IAC or TPS switch. When I come to a stop at a light the idle will dip to about 400rpms and sound like it wants to stall. If i put in neutral the idle will come back to the 650 idle then put back into drive and will idle ok until my next stop. Well i tried putting the car into neutral before i come to a stop and the idle will be ok. I feel its something when the engine is engaged in drive and might be something in the tranny causing this erratic Idle.
Is it possible that something in the tranny might cause this? The tranny shifts good with no problems. I do detect that a slow down shift when i come to a stop like an extra shift. Could something like this cause the idle to be sucked down to the 400rpms. Again there are times when I come to a stop and the idle would be good.

thanks

[xj31]

It's possible that you might be low on trans fluid.I know that might sound stupid but the trans you have needs fluid pressure to turn off the clutch in the torque converter.If its low the clutch stays on and it can even stall the engine.