When I shift my car from any gear to neutral while approaching a stop light, sign, driveway, etc., it nearly stalls but never does. The idle goes down to 300-400 RPM briefly and then recovers to 800 RPM. This is where the base idle is set(800 RPM). Can anyone tell me what causes this? What component of the car is responsible for catching the falling engine speed before the car stalls out? Thanks for your help, guys. By the way, the car in question is a 1992 Sentra SE-R.