This is what you do. Take apart the faucet to see if there's any
obstruction. If that doesn't work, take the supply lines apart (there
aren't screens in there, but don't make fun of your wife), if that doesn't
work, the next suspects are the stop valves. Shut off the house valve and
take them apart or replace them. If that doesn't work, then it's the
galvanized pipes. That doesn't mean you have to repipe the whole house. A
good plumber is a good detective, and can often isolate the problems without
replacing everything. If you have galvanized pipes, though, it might be
good to repipe if you can afford it.
BTW, it's been my experience that when non-plumbers take things apart,
they can't get them back together.