ENGINE CUTS OUT?

WHEN ENGINE HAS WARMED UP ,EVERY TIME I SLOW DOWN AT JUNCTION OR LIGHTS ECT, IT CUTS OUT OR TRIES TO THEN NO POWER TO BREAKS OR STEERING
I CAN SOMETIMES CATCH THIS BY GIVING THE THROTTLE A BLIP AND THEN IT WILL RUN AGAIN FINE UNTILL THE NECT TIME I SLOW TO A STOP,BY THE WAY ITS O K WHEN I SLOW AND SPEED UP IN TRAFFIC,YOU CAN FEEL A SLIGHT LOSS OF POWER TO THE STEERING WHEN YOU HAVE TO SLOW DOWN FAST