I have a Price/Pfister single handle kitchen faucet with a peculiar problem. The faucet is about fire years old and recently started acting strangely. If I turn the faucet on after it has been sitting for 15-20 minutes, I get full flow immediately. If I turn the faucet off for a few seconds and then turn it back on the flow is reduced by half. If I use the hose sprayer while the faucet is on, the flow goes back to full strength immediately. I tried replacing the valve insert with a new one (under warranty) but the problem persists. I do not have this problem with any other faucet in the house. Ideas?