2001 Hyundai Elantra high up and down RPM idle, the extreme

My daughter's 2001 Elantra has been throwing a 0303 ODS code for a month now. Coil, plugs and plug wires have all been replaced.

Now car won't slow idle but when cold, idle runs up and down from 1000 to 2500 then as warms just idles faster and faster, up to 5000 RPM. If Idle Speed Control is disconnected, idle will drop but fluctuate between 500 and 1200 RPM. Car shbws a 0303 code(misfire on #3 cyl.) And a 0121 code (throttle position sensor problem.)

The carb cleaner vacuum leak check seems to indicate a leak around the intake manifold at the #3 cylinder.

Would a cracked intake manifold or gasket cause these symptoms?