Brake booster vacuum pump
 

Brakes work fine while you are driving,but when you come to a stop and your engine is at idle,I start to lose my power brakes.Everything I read points to the vacuum pump.Does anyone know if there is anything to clean or do to the original pump or dont waste my time and replace it.My X5 is a 2006 4.4.Thanks for any help.And I have replaced the vacuum line from the pump to the booster check valve.Thanks