1990 Chrysler 5th Avenue Rough Idle

Once the engine has reached operating temperature and I come to a red light idle the motor loses its RPM and starts to sputter. The motor runs as if it is flooding and has no increase in RPM again to power the car in a forward motion.
If the ignition is turned off for about 3 to 5 seconds and then I restart the motor it runs smoothly until the next red light stop.
Thanks for your help and "˜Have a Good Day’
Tarus