Pontiac Sunfire won't start

Right after I got an oil change four months ago, I tried to turn on my car but it wouldn’t start. (I’m guessing this is not related to the oil change) The starter spun but was not engaging with the fly-wheel. I towed the car home and replaced the starter myself. It appeared as though the solenoid wasn’t engaging the gear with the flywheel. Now the starter turns the engine over very very slowly at a snails pace but doesn’t start the engine. I hooked it up to another battery and it just did the same. I took the newest (still used) started out from the car and bench tested it and it passed just fine. Also, I just replaced the plugs and everything else looks okay around the engine, but it just won’t turn very fast and won’t start. Any ideas?



Miles: 129,933

Engine: 2.2L L4 FI SOHC 8V

Also, it’s a 2001.