Cavalier poor mpg

My cavalier has a pcv hose conected from the valve cover to the intake tube. I replaced stock intake w/k&n typhoon intake system. At the pcv hose connection w/the valve cover oil seaps out and the hose sometimes slips off. There is also oil evident in the intake tube itself. Could the pcv system cause excesive fuel comsumption? The haynes repair manuel says there might be blow by or too much crankcase pressure.

I have a 98 chevy caviler and the gas milage has gone way down. Im down to about 10 MPG, when I used to get about 23. Do you think it has gone down like this because of bad compression? Do you have any ideas for the reason why my gas milage is declining?

The engine seems to be running fine but the check engine soon light is on. I scanned the car and it said to check the mass air flow sensor. I checked that and everything was fine. And I just changed my oil, air filter, tranny fluid, and tranny filter.

Yes.

It said there was a problem with the mass flow intake senor. It didnt make much sense on the location of which one it was because its not a V6. But it doent matter anymore because my trnny is going to blow up soon. Thank you for your time