89 jetta rpms drop

89 jetta engine 8 valves shutters -rpms dropped when i have to stop fast from about 60 mph- rpms dropped to 600. engine stalled afterwards.
i have new plugs and new air filter.

You need to clean your idle stabilizer valve. Remove it and use carb cleaner on it.

i had the same problem. yes u should clean the idle stabilizer valve, but to make it run even smoother...
get the car up to temp and unplug the isv. next u will find the idle bypass screw on the closet side of the throttle body inside o f the metal housing. unscrew it until it idles at about 925rpms. plug ur isv back in and ur good to go. that circuit is unreliable and dosn't always work right. if u do this u should see a slight gain in acceleration.