Kitchen Sink pressure problem
We had the same problem, took it to dealer, they figured it out after much diagnosis. Good pressure when using pump, bad when on city. Turned out a small metal shaving had made its way to the faucet, a restricter is located somewhere in the flexible line that pulls out from faucet. When the lower pump pressure was used it did not press so hard on the debris, and actually had adequate pressure. But when you put full city pressure (40lb regulator) it pushed harder on the debris and restricted flow. They cleaned that out and now it works perfect! Very difficult to diagnose because you would think if you have good pump pressure, you would have good city pressure.