The CP3 pump regulator controls the fuel pressure that is being sent to the injector fuel rails and the injectors themselves. Over time these will wear out or be contaminated causing inaccurate pressure control. It is common to have an uneven idle or a loping idle. If the problem is bad enough the varying idle RPM can cause the vehicle to want to move while stopped. Bosch is including three new mounting screws now also!
Typical life expectancy of the CP3 pump is 150,000 miles. If your pump is near or past this mileage our recommendation is to not replace just the regulator, but instead install a whole new pump that comes with a new regulator installed.
Old part number = Bosch 0928400673