I have a late '97 Eddie Bauer Ford Expedition with the 5.4-liter Triton engine. It has the air suspension system and it seems that, when you are looking at the vehicle from the rear, that the body is not level. I have measured the clearance from the wheel wells to the ground at both sides of the vehicle, and found out that one side of the vehicle is one and one half inches lower than the other. I have tried to reset the air suspension switch just like the manual indicated, but to no avail.
Determining ride height at the wheel well moldings is not an accurate method. The actual procedure requires measurements at specific reference points between the frame and rear axle. But, if there is clearly a visible lean to one side, then we obviously have a problem.
The Expedition's "Electronic Suspension" system comes in two versions. The 2WD set-up controls only the rear suspension and the 4x4 system affects all four wheels with the use of air shocks in the front. However, both systems utilize two rear air springs which replace the conventional steel coil springs and are controlled in unison, not left-right. So, that eliminates a calibration failure and leaves us with choices such as an obstructed airline, a faulty air spring solenoid valve, or a "strong candidate" would be a defective air spring unit itself. There are also possibilities unrelated to the system, like frame damage, a mispositioned body mount, etc.
Your resetting of the air suspension switch simply started the system over at its default settings, but an important thing to remember is to use this switch to shut down the system when lifting the vehicle off the ground to prevent over inflation of the air springs and/or shocks.