We are having low water pressure from our kitchen sink and master bathroom shower. Everywhere else the water is fine. This occurred approximately two years ago as well. We eventually changed the faucet (about a year ago) and that fixed the problem in the sink. The shower problem seemed to fix itself about a month after it started. We also have a fairly new water heater. The kitchen sink has a sprayer and the water pressure there is also low, sometimes so low that it doesn't spray at all!

What should I do to fix this problem?

Kitchen faucet: Remove aerator, run water w/o it, clean aerator, reinstall. Sprayer is attached to kitchen faucet. There is a diverter built inside the faucet. You will have to disassemble the faucet to check on it and clean it. It is most likely clogged with debris..

Shower head: remove shower head, run water w/o shower head installed, clean filter screen inside the shower head and reinstall.

That should do...