2000 Nissan Maxima idling

Engine Performance problem
2000 Nissan Maxima 6 cyl Front Wheel Drive Automatic

at times there is a problem with the idling, and everytime you rev it to 2,000 or 3,000 or 4,000 rpm and let off of the gas it falls down to idle speed and then continues to fall until it dies. But the car runs and performs well.