Remove the rear seat to access the trunk and repair the lock assembly.
first i would try the oil pan
You must first remove the trunk door facia. (This is the part with the "Pontiac" lights in it.) Then you can get to the bulb to replace it.
Flat side first
To change the license plate light on a Pontiac Sunfire, first remove the cover over the bulb with a small screwdriver. Gently push on the bulb and turn 1/4 turn to remove the old bulb. Insert the new bulb and snap in the cover.
check your fuses first, then check your bulbs and then your relay.
take the wheel well out first then reach in and turn bulb socket
it "should" be to the right side and bellow steering wheel .if it is equipped with one.maybe check at trunk latch first to determine the car has this"option" In my 2001 Sunfire, it is on the left side bellow the steering wheel.
You need to convert the AC system to R-134a type freon first (retrofit kit). Then you charge it on the low pressure side.
Near the rear of the vehicle up near the gas tank; RELIEVE FUEL PRESSURE FIRST BEFORE REMOVING THE FILTER!!!
First make sure all spark plugs are in good shape; check the IDLE CONTROL VALVE maybe need to be clean or better yet replace.
pontiac first started out in 1926
Sometimes a ticking sound is a valve lifter. The faster you go the faster the ticking will be. Make sure first it is not something stuck in a tire or something on the fan belt.