Stalling Pacifica

My 2004 AWD has taken to stalling when I start it--it starts readily but then immediately stalls. Happens repeatedly--always starts easily and runs fine with the accelerator pressed, but when I let off the accelerator and the RPMs slow toward idle, it stalls. Then, other times, it runs perfectly. The problem seems to run in streaks--some days it happens every time I drive, other times it won't happen for a couple of weeks. I have had a friend put a code reader on the car and no codes are being stored. I am stumped. Any thoughts or suggestions would be appreciated.
Thanks.

Try cleaning the throttle body, throttle plate(backside) and IAC.

check the throttal position sensor if cleaning the t.plates don't do any good. wiggle the connector it might give you a sign