I had this exact problem on my '97 I4 Camry. You need to clean the throttle
plate and throttle body walls using a O2 & CAT safe throttle body cleaner.
While your there you should also clean the IAC motor valve by squirting the
cleaner into the curved rectangular opening at the mouth of the throttle body.

Marvin

Get some aerosol carburetor cleaner or throttle body cleaner that is O2
sensor and catalytic converter-safe (I think pretty much all of it is now),
some rags or paper towels, a 10 mm socket and ratchet, and that silicone
lube.

Follow the large diameter black rubber hose from the air cleaner housing to
the throttle body, which is the cast aluminum housing near the engine.

With the engine off, use the 10 mm socket and ratchet to loosen the hose
clamp that holds the hose to the throttle body and remove the hose.

After the hose is out of the way, you will see the throttle plate - it looks
like the butterfly valve on a carburetor.  Pull on the bell crank that the
throttle cable is attached to open the throttle plate.  The edge of the
plate, back side, and inside of the throttle body are probably gummed up and
will appear brown or black.  The gum on the edge of the plate sticks to the
inner circumference of the throttle body, making the gas pedal hard to
depress.

Spray the back side of the throttle plate and use the rag or paper towel to
wipe it clean, paying attention to the edges and where the rod that the
plate pivots on passes through the throttle body.  Also spray and wipe as
much of the inside of the throttle body as you can reach.  The cleaner is
highly flammable, so you don't want to be smoking or have any sources of
heat or flame nearby.  Wipe as much of the cleaner out as you can.

Spray a little silicone lube on the outside of the throttle body where the
hose fits to make the hose easier to slide on and re-attach the hose.

When you start the engine, it may run a little rough and smoke a little, let
the engine run until it dissipates and you should be good to go.

Good luck!