has anyone experienced a problem like this with a 2.4L, when the car is cold, like when starting it up in the morning. that when u shift or brake to a stop, the revs will just drop and the car will stall, but then when it gets warm, the car will run fine?

Somthing might be wrong with one of your Coils...Creates the sparks for the plugs if ya didn't know.

or maybe try the coolant temp sensor,if so it would be a cheap fix, around $8

Please clean the IAC Valve. The coils nor the coolant temp sensor cause this. Coils certainly do not get better when warm. Good Luck.