[gascort]

Aeromodder, you may have the same circuitry in your car as my escort has. (with lean burn)... I've only found a thing or two on the internet about it; apparently Ford called it LOC (Lean On Cruise).
Mpguino and others' wide band O2s have verified this; when the car's warm and in closed loop for a few seconds at light throttle and at speed, it re-enters open loop and increases AFR (air to fuel ratio) up to around 17:1 (If I remember correctly).
If I watch my iMPG on my MPGuino on a flat stretch while going 60-ish mph, I see numbers go between high 30s and mid 50s when this switches on and off.

My goal is to get the car aero and low engine drag enough to do this part time thing at 65-70 mph and all the time at 55-60 mph - would let me get into the 50s.