I have  a pull behind sprayer with raven controls and installed JD rate controller. I have had the rate controller for a couple of years. However since ive installed the rate controller I have to go slower to achieve the targeted GPA. I could drive much faster with the Raven SC440 controller. Have I missed some other calibration step?. IT also seems when I first start a field the targeted rate and desired speed is achievable however the longer I run the slower I have to go. filters etc are clean and pressure is staying at the targeted PSI.  thanks