2000 eclipse gt dont run right?

My eclipse started missing and it wont idle and. It was running really rich at how rpms and started getting really bad gas mileage. I was getting about 20 and now im getting about 10. When I unplug my mass air flow sensor it runs alot better and it idles good but it still don't have as much power as it did. Would my mass airflow sensor be bad. And I tried pugging a computer in to scan it to and there's no power at the port. What would cause that. Thanks