Our kitchen faucet normally has excellent water pressure. However, of late, it has dwindled to 50% of normal pressure. If our water has been off for any reason, when it comes back on there are pieces of junk that are stirred up and will have to be cleaned out of the aerator and screen. I have checked this butth epressure is still low. I have taken off the handles and taken apart the hot and cold water valves but cannot find anything wrong. could it be in the shutoff valve under the sink?