I just went and got my oil changed and they told me I had some parts missing off my car. My oh so wonderful ex boyfriend, stole parts off my car. I was wondering if they were important or if I didn't need to worry about it. They told me that the cap (the top parts) off of my air filter is missing. Do I need to try to find the parts and buy them or is it ok without it? My car is a 1993 Chevy Cavalier z24. Thanks!

You should have that part installed. The airbox parts help to protect the filter from debris and water, and help the engine function correctly.
It isn't a critical part; but it is an important one.

Try a junkyard for that cap, should save you money.