My 97 cavalier is sluggish could it be my o2 sensor or the catalaic converter I changed the plugs already it just doenst have any power and also it is throwing oil out my exhaust

Sounds like a blown head gasket...

What mixture are you running with? Try a good quality synthetic blend with two stroke oil if running hard. Sometimes it's normal and the only issue is that you're running too rich. Better take a spark plug reading.