On my 2002 Ford Explorer XLT, there is a vacuum tube on the Passenger side that came loose which caused this. When this happened, I heard a hissing from under the passenger side dash . The vacuum tube has a "T" connector. To reconnect, find the oval shaped cylinder and attach the "T" connector to the end being sure to insert it fully.
The Mass Air Flow sensor is located on top of the air filter housing on Ford Explorer.
On a 1998 Ford Explorer : The Mass Air Flow Sensor is between the engine air filter and the big engine air intake tube
Kool Vue muffler, Walker Muffler, and Flow Master are good brands for a 01 Ford Explorer.
Hi, It is not the blend door, that is for heat/cold changes. The mode door could be the problem, or stuck defrost door.
On a 1998 Ford Explorer : The mass air flow sensor is between the engine air filter and the big rubber engine air intake tube
On your 1998 Ford Explorer Sport : The mass air flow sensor is between your engine air filter and the big rubber engine air intake tube
On a 2002 Ford Explorer : The Mass Air Flow sensor is between the top section of the engine air filter housing and the engine air intake tube
On a 2001 Ford Explorer : The Mass Air Flow sensor is located between the engine air filter housing and the large diameter engine air intake tube
On a 1994 Ford Explorer : The Mass Air Flow sensor is located between the top section of the engine air filter housing and the engine air intake tube
On a 1992 Ford Explorer : The Mass Air Flow sensor is located between the top section of the engine air filter housing and the big rubber engine air intake tube
P0401 - EGR flow insufficient , P0402 EGR flow excessive
Between the air filter box and the throttle body.