Replaced Mass Airflow Sensor on the 3.0L w/110000 miles. New codes now, PO400, P1100 and PO800. No significant driving problems though but poor fuel mileage, around 16mpg is best my son ever gets. Is the AWD model. Thanks.

 

Sounds ilogical (EGR + MAP + Transfer case/Center differential). Most probably there's some unfitted connector or something like that.