I am new to this forum. I was trying to figure out a problem with my idle. The problem occurs when the defroster or A/C is selected and the fan is running (trans in drive). What happens when these options are selected: I start slowing down below 20mph, and the engine acts like it is going to stall. It does this once in a while when the fan is off and the a/c and defroster is off. I know it is not the idle sensor, it does not have a rough idle, and the idle is consistant. I was wondering what other sensor(s) would have the effect I described above with the idle (when the trans is in drive)?

99' Dodge Avenger 2.5 v-6 (auto)