. THE ENGINE MOUNTED MECHANICAL VACUUM PUMP MAY DECREASE OVER TIME DECREASING THE AMOUNT OF VACUUM/ POWER BRAKE ASSIST, CAUSING VEHICLE NOT TO STOP. SAME AS MY 2016 GMC. I HAD TO ALSO HAVE THE ( EVAP CONTROL VALVE REPLACED). TRANSMISSION SURGES AND ON THE DOWN SHIFT ITS KNOCKING COMING TYO A STOP. .IN MY REAR ENDING A PARKED VEHICLE BECAUSE OF THE BRAKES PULSATING AND NOT STOPING SCARED ME. .DEALERSHIP. .DEALERSHIP .NO