First, check the specification for idle speed because 700 RPM does not sound
too low.  The specification should be on a label in the engine compartment,
either near the radiator support beam or on the underside of the hood.

Second, many "oil change mechanics" who do nothing but oil changes are not
knowledgeable enough to diagnose problems.  For example, a bad PCV valve
does not usually affect idle speed, as you have discovered.

Check the idle air control (IAC) valve on the throttle body.  If it appears
to be gummed up, try cleaning it with carburetor cleaner.  The IAC valve
controls how much air enters the engine at idle.

Also check the mass air flow (MAF) sensor located on the air filter housing.
There is a tube that protrudes into the air flow, and there is a wire inside
of the tube.  The MAF sensor is not supposed to be serviceable, but you can
try cleaning it with rubbing alcohol or carb cleaner and a cotton swab.  If
the wire breaks, you will need a new MAF sensor.  The wire becomes coated
with an oily residue or dirt over time, and that coating will affect idle
speed.

You might try cleaning the Idle Air Control (IAC) valve.